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| 18 | <td valign=center>
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| 19 | <a href="index.html">
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| 20 | <font color="#004faf">Home</font></a>
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| 21 | | <a href="classes.html">
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| 22 | <font color="#004faf">All Classes</font></a>
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| 23 | | <a href="mainclasses.html">
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| 24 | <font color="#004faf">Main Classes</font></a>
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| 25 | | <a href="annotated.html">
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| 26 | <font color="#004faf">Annotated</font></a>
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| 27 | | <a href="groups.html">
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| 28 | <font color="#004faf">Grouped Classes</font></a>
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| 29 | | <a href="functions.html">
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| 30 | <font color="#004faf">Functions</font></a>
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| 31 | </td>
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| 32 | <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>The Qt FAQ</h1>
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| 33 |
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| 34 |
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| 35 | <p>
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| 36 | <p> See also the <a href="commonproblems.html">Technical FAQ</a>.
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| 37 | <p> <!-- toc -->
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| 38 | <ul>
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| 39 | <li><a href="#1"> General Questions
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| 40 | </a>
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| 41 | <ul>
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| 42 | <li><a href="#1-1"> What is Qt?
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| 43 | </a>
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| 44 | <li><a href="#1-2"> What is Trolltech?
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| 45 | </a>
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| 46 | <li><a href="#1-3"> How can I evaluate Qt?
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| 47 | </a>
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| 48 | <li><a href="#1-4"> What does Qt cost?
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| 49 | </a>
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| 50 | <li><a href="#1-5"> How can I buy Qt?
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| 51 | </a>
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| 52 | <li><a href="#1-6"> What kind of technical support is available for Qt?
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| 53 | </a>
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| 54 | <li><a href="#1-7"> Who provides training for Qt?
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| 55 | </a>
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| 56 | <li><a href="#1-8"> Who provides consultancy for Qt?
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| 57 | </a>
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| 58 | <li><a href="#1-9"> Are there any books about Qt programming?
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| 59 | </a>
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| 60 | <li><a href="#1-10"> What is the Open Source Edition?
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| 61 | </a>
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| 62 | <li><a href="#1-11"> What is the idea behind having a free version of Qt?
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| 63 | </a>
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| 64 | <li><a href="#1-12"> Is there a low-cost version of Qt for writing shareware?
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| 65 | </a>
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| 66 | </ul>
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| 67 | <li><a href="#2"> Questions about Qt's Users
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| 68 | </a>
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| 69 | <ul>
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| 70 | <li><a href="#2-1"> How many developers use Qt?
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| 71 | </a>
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| 72 | <li><a href="#2-2"> Which major corporations use Qt?
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| 73 | </a>
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| 74 | <li><a href="#2-3"> Are there any well-known applications that use Qt?
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| 75 | </a>
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| 76 | </ul>
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| 77 | <li><a href="#3"> Questions about Developing Applications with Qt
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| 78 | </a>
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| 79 | <ul>
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| 80 | <li><a href="#3-1"> Is there a mailing list for Qt?
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| 81 | </a>
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| 82 | <li><a href="#3-2"> Is Qt's documentation available online?
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| 83 | </a>
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| 84 | <li><a href="#3-3"> Is there a technical newsletter for Qt?
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| 85 | </a>
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| 86 | <li><a href="#3-4"> I think I have found a bug in Qt. Where can I report it?
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| 87 | </a>
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| 88 | </ul>
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| 89 | <li><a href="#4"> Questions about Professional Licensing
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| 90 | </a>
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| 91 | <ul>
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| 92 | <li><a href="#4-1"> We have purchased a license, but the developer is leaving the company
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| 93 | project. Can we transfer the license to another developer?
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| 94 | </a>
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| 95 | <li><a href="#4-2"> Can I purchase floating licenses for Qt?
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| 96 | </a>
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| 97 | <li><a href="#4-3"> Can we use the Open Source Edition while developing our non-free
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| 98 | application and then purchase commercial licenses when we start to
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| 99 | sell it?
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| 100 | </a>
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| 101 | </ul>
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| 102 | <li><a href="#5"> Questions about Open Source Software Licensing
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| 103 | </a>
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| 104 | <ul>
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| 105 | <li><a href="#5-1"> I just want to run KDE and other Qt-based software on my
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| 106 | machine. Can I do that with the Open Source Edition?
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| 107 | </a>
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| 108 | <li><a href="#5-2"> I want to put Qt, and applications that use it, on a CD-ROM or on
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| 109 | a web site. Can I do that with the Open Source Edition?
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| 110 | </a>
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| 111 | <li><a href="#5-3"> Can I make software with the Qt Open Source Edition and release it under
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| 112 | the GNU GPL, BSD, or Artistic license?
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| 113 | </a>
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| 114 | <li><a href="#5-4"> I don't want to give away my source code. What do I do?
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| 115 | </a>
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| 116 | <li><a href="#5-5"> Is software based on the Qt Open Source Edition really free? Does it
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| 117 | carry any Trolltech-specific license restrictions?
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| 118 | </a>
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| 119 | <li><a href="#5-6"> What if Trolltech stops releasing Open Source Editions of Qt?
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| 120 | </a>
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| 121 | <li><a href="#5-7"> Using the Open Source Edition, can I make non-free software for internal
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| 122 | use in my company/organization?
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| 123 | </a>
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| 124 | <li><a href="#5-8"> Is Qt Open Source Edition really free software in the GNU meaning of the
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| 125 | word?
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| 126 | </a>
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| 127 | <li><a href="#5-9"> If the Open Source Edition is GNU GPL, aren't there license conflicts
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| 128 | with incompatible open source licenses? How come people can even
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| 129 | run commercial software like the Opera web browser with it?
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| 130 | </a>
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| 131 | <li><a href="#5-10"> Doesn't such an en extra license in addition to the GNU GPL
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| 132 | violate the terms of the GPL or at least make the whole package
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| 133 | GPL-incompatible?
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| 134 | </a>
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| 135 | <li><a href="#5-11"> Why is Qt Open Source Edition not distributed under the GNU Lesser
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| 136 | General Public License (LGPL)?
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| 137 | </a>
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| 138 | </ul>
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| 139 | <li><a href="#6"> Questions about other programming languages
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| 140 | </a>
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| 141 | <ul>
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| 142 | <li><a href="#6-1"> Are there bindings to languages other than C++?
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| 143 | </a>
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| 144 | <li><a href="#6-2"> Can I develop commercial applications with PerlQt or PyQt or other
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| 145 | Qt wrappers?
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| 146 | </a>
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| 147 | </ul>
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| 148 | </ul>
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| 149 | <!-- endtoc -->
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| 150 |
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| 151 | <p> <hr>
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| 152 | <h2> General Questions
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| 153 | </h2>
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| 154 | <a name="1"></a><p> <hr width="30%">
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| 155 | <h3> What is Qt?
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| 156 | </h3>
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| 157 | <a name="1-1"></a><p> Qt is a multiplatform C++ GUI toolkit. It
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| 158 | provides application developers with all the functionality
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| 159 | needed to build applications with state-of-the-art graphical
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| 160 | user interfaces. Qt is fully object-oriented, easily
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| 161 | extensible, and allows true component programming.
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| 162 | <p> Qt is supported on the following platforms:
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| 163 | <p> <ul>
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| 164 | <li> <b>MS/Windows</b> -- 95, 98, NT 4.0, ME, 2000, and XP
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| 165 | <li> <b>Unix/X11</b> -- Linux, Sun Solaris, HP-UX, Compaq Tru64 UNIX,
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| 166 | IBM AIX, SGI IRIX and a wide range of others
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| 167 | <li> <b>Macintosh</b> -- Mac OS X
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| 168 | <li> <b>Embedded</b> -- Linux platforms with framebuffer support.
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| 169 | </ul>
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| 170 | <p> It has become the emerging standard development
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| 171 | environment for IT professionals who want to:
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| 172 | <p> <ul>
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| 173 | <li> Write (and maintain) a single source-tree.
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| 174 | <li> Port their applications to multiple platforms with a simple
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| 175 | recompilation.
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| 176 | <li> Internationalize their applications.
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| 177 | <li> Provide their applications with native look and feel.
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| 178 | <li> Have their applications run at native speed.
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| 179 | </ul>
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| 180 | <p> <hr width="30%">
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| 181 | <h3> What is Trolltech?
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| 182 | </h3>
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| 183 | <a name="1-2"></a><p> Trolltech is an international software company with
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| 184 | headquarters in Oslo, the capital of Norway, and with offices
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| 185 | in Brisbane, Australia, and Redwood City, California. Our
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| 186 | flagship product is Qt, the multi-platform C++ GUI toolkit.
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| 187 | <p> Trolltech ASA was founded in 1994, although, the core team of designers
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| 188 | started Qt's development in 1992.
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| 189 | <p> More details can be found at <a href="troll.html">Trolltech</a>.
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| 190 | <p> <hr width="30%">
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| 191 | <h3> How can I evaluate Qt?
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| 192 | </h3>
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| 193 | <a name="1-3"></a><p> We offer 30 day evaluation versions of Qt on all our supported platforms.
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| 194 | Further details can be found here: <a href="http://www.trolltech.com/evaluate.html">http://www.trolltech.com/evaluate.html</a>.
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| 195 | <p> <hr width="30%">
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| 196 | <h3> What does Qt cost?
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| 197 | </h3>
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| 198 | <a name="1-4"></a><p> This depends on your number of developers, on how many
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| 199 | different platforms you target, and on the edition of Qt you
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| 200 | choose. Currently we offer two different editions (Enterprise
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| 201 | Edition and Professional Edition) on four different
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| 202 | platforms (Microsoft Window, Unix/X11, Macintosh and Linux/embedded).
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| 203 | <p> We also offer discounts for academic and research institutions.
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| 204 | <p> Details on pricing can be found here:
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| 205 | <a href="http://www.trolltech.com/pricing.html">http://www.trolltech.com/pricing.html</a>.
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| 206 | <p> <hr width="30%">
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| 207 | <h3> How can I buy Qt?
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| 208 | </h3>
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| 209 | <a name="1-5"></a><p> To purchase, please visit the <a
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| 210 | href="https://webshop.trolltech.com/cgi-bin/index.cgi">Trolltech
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| 211 | webshop</a>. In the webshop, you can generate a Purchase Order, order
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| 212 | a Quote, or purchase directly using a credit card.
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| 213 | <p> For further information and assistance, please contact Trolltech sales:
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| 214 | <p> Email: <a href="mailto:sales@trolltech.com">sales@trolltech.com</a>
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| 215 | Phone, US office (for North America): <strong>(+1) 650-813-1676</strong>
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| 216 | Phone, Norway office (for others): <strong>+47 2160 4800</strong>
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| 217 | <p> <hr width="30%">
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| 218 | <h3> What kind of technical support is available for Qt?
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| 219 | </h3>
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| 220 | <a name="1-6"></a><p> Trolltech offers email support to commercial licensees. The first year
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| 221 | of Trolltech's Support and Maintenance Service is included with the
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| 222 | purchase of Qt Professional and Qt Enterprise Edition licenses.
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| 223 | Licenses can be kept up-to-date and fully supported by buying
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| 224 | the Support and Maintenance Service for the licenses held in each
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| 225 | subsequent year.
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| 226 | <p> For further information see here:
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| 227 | <a href="http://www.trolltech.com/support/">http://www.trolltech.com/support/</a>.
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| 228 | <p> <hr width="30%">
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| 229 | <h3> Who provides training for Qt?
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| 230 | </h3>
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| 231 | <a name="1-7"></a><p> A number of companies provide Qt training, in Asia, Europe and the US.
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| 232 | Trolltech has agreements with a number of official training
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| 233 | partners, who offer Trolltech approved courses. In addition
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| 234 | there are a number of independently developed courses run by third
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| 235 | parties. You can find more information about the partners and the
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| 236 | courses here: <a href="http://www.trolltech.com/training/">http://www.trolltech.com/training/</a>.
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| 237 | <p> <hr width="30%">
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| 238 | <h3> Who provides consultancy for Qt?
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| 239 | </h3>
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| 240 | <a name="1-8"></a><p> A number of companies provide consultancy services for Qt and
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| 241 | Qtopia. You can find a partial list here:
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| 242 | <a href="http://www.trolltech.com/company/servicepartners.html">http://www.trolltech.com/company/servicepartners.html</a>.
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| 243 | <p> <hr width="30%">
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| 244 | <h3> Are there any books about Qt programming?
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| 245 | </h3>
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| 246 | <a name="1-9"></a><p> Yes, there are quite a few books on Qt, most of them
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| 247 | available from amazon.com. You can find a partial list at
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| 248 | <a href="http://www.trolltech.com/developer/books.html">http://www.trolltech.com/developer/books.html</a>.
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| 249 | <p> The official Qt book is
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| 250 | <a href="http://www.amazon.com/exec/obidos/ASIN/0131240722/trolltech/">C++ GUI Programming with Qt 3</a>.
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| 251 | <p> <hr width="30%">
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| 252 | <h3> What is the Open Source Edition?
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| 253 | </h3>
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| 254 | <a name="1-10"></a><p> The Qt Open Source Edition is our non-commercial versions of
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| 255 | Qt. You can use this edition to create and run free
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| 256 | software, i.e. software that is licensed under the GNU GPL or
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| 257 | a similarly recognized open source license.
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| 258 | <p> Qt Open Source edition is available for Unix/X11, Macintosh and
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| 259 | Linux/embedded.
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| 260 | <p> <hr width="30%">
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| 261 | <h3> What is the idea behind having a free version of Qt?
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| 262 | </h3>
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| 263 | <a name="1-11"></a><p> With the Open Source Edition, Trolltech has found a way to support
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| 264 | the free software concept. Part of our commitment is to enable
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| 265 | those who contribute to the free software pool to do so
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| 266 | without paying license fees.
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| 267 | <p> <hr width="30%">
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| 268 | <h3> Is there a low-cost version of Qt for writing shareware?
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| 269 | </h3>
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| 270 | <a name="1-12"></a><p> No, but Qt's commercial licenses permit you to write and sell
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| 271 | shareware written with Qt.
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| 272 | <p> <hr>
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| 273 | <h2> Questions about Qt's Users
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| 274 | </h2>
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| 275 | <a name="2"></a><p> <hr width="30%">
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| 276 | <h3> How many developers use Qt?
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| 277 | </h3>
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| 278 | <a name="2-1"></a><p> We don't know! We can count our many thousands of commercial
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| 279 | licensees, but the number of free software developers
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| 280 | using Qt can only be guessed based on download figures, book
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| 281 | sales, the number of open source Qt applications available on
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| 282 | the web, Universities teaching with Qt, and other factors. A
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| 283 | conservative estimate would put the figure at around 100,000 to
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| 284 | 150,000 developers world-wide.
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| 285 | <p> <hr width="30%">
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| 286 | <h3> Which major corporations use Qt?
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| 287 | </h3>
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| 288 | <a name="2-2"></a><p> See our list of reference customers at
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| 289 | <a href="http://www.trolltech.com/company/customers.html">http://www.trolltech.com/company/customers.html</a>. Note that many
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| 290 | commercial customers do not disclose their use of Qt because they see
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| 291 | Qt as a competitive advantage.
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| 292 | <p> <hr width="30%">
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| 293 | <h3> Are there any well-known applications that use Qt?
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| 294 | </h3>
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| 295 | <a name="2-3"></a><p> There are many, e.g. Adobe Photoshop Album from Abobe
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| 296 | Corporation and the KDE desktop. A partial list can be found at
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| 297 | <a href="http://www.trolltech.com/products/qt/apps-using-qt.html">http://www.trolltech.com/products/qt/apps-using-qt.html</a>
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| 298 | <p> <hr>
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| 299 | <h2> Questions about Developing Applications with Qt
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| 300 | </h2>
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| 301 | <a name="3"></a><p> <hr width="30%">
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| 302 | <h3> Is there a mailing list for Qt?
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| 303 | </h3>
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| 304 | <a name="3-1"></a><p> Trolltech operates several mailing lists for Qt users including
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| 305 | <tt>qt-announce</tt>, <tt>qt-interest</tt> and <tt>snapshot-users</tt>.
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| 306 | <p> See <a href="http://lists.trolltech.com">Mailing lists</a>.
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| 307 | <p> <hr width="30%">
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| 308 | <h3> Is Qt's documentation available online?
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| 309 | </h3>
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| 310 | <a name="3-2"></a><p> Yes, at <a href="http://doc.trolltech.com">http://doc.trolltech.com</a>.
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| 311 | <p> <hr width="30%">
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| 312 | <h3> Is there a technical newsletter for Qt?
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| 313 | </h3>
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| 314 | <a name="3-3"></a><p> Yes, <a href="http://doc.trolltech.com/qq/index.html">Qt
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| 315 | Quarterly</a>. It is a paper-based newsletter exclusively
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| 316 | available to Qt licensees.
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| 317 | <p> As a courtesy and convenience to all our users, a selection of
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| 318 | articles is also published online about one month after publication.
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| 319 | <p> <hr width="30%">
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| 320 | <h3> I think I have found a bug in Qt. Where can I report it?
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| 321 | </h3>
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| 322 | <a name="3-4"></a><p> Bugs should be reported to <a href="mailto:qt-bugs@trolltech.com">qt-bugs@trolltech.com</a>. But <em>please</em> read (the very short)
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| 323 | <a href="bughowto.html">How to Report a Bug</a> page <em>first</em>.
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| 324 | <p> <hr>
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| 325 | <h2> Questions about Professional Licensing
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| 326 | </h2>
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| 327 | <a name="4"></a><p> <hr width="30%">
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| 328 | <h3> We have purchased a license, but the developer is leaving the company
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| 329 | project. Can we transfer the license to another developer?
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| 330 | </h3>
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| 331 | <a name="4-1"></a><p> Yes. Qt licences are for the individual use of named developers. If
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| 332 | the developer associated with a licence leaves the organization, or
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| 333 | moves on to another project that does not require a Qt license,
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| 334 | another developer can take over the licence. You can change the name
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| 335 | of the developer using a licence at any time, but after a change you
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| 336 | must wait at least six (6) months before changing again.
|
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| 337 | <p> <hr width="30%">
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| 338 | <h3> Can I purchase floating licenses for Qt?
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| 339 | </h3>
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| 340 | <a name="4-2"></a><p> No, we do not offer floating licenses.
|
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| 341 | <p> The reason is this: Floating licenses are based on the concept
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| 342 | of defining a maximum number of concurrent users. For example,
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| 343 | for a word processor, this means the maximum number of
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| 344 | instances of that application that can be running at any
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| 345 | time. However, for a library product like Qt, there is no main
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| 346 | application that is always running when the product is being
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| 347 | used. Hence, it is not possible to count the number of
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| 348 | concurrent users, and therefore floating licenses do not
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| 349 | make sense.
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| 350 | <p>
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| 351 | <p> <hr width="30%">
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| 352 | <h3> Can we use the Open Source Edition while developing our non-free
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| 353 | application and then purchase commercial licenses when we start to
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| 354 | sell it?
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| 355 | </h3>
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| 356 | <a name="4-3"></a><p> No: our commercial license agreements only apply to software
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| 357 | that was developed with Qt under the agreement. They do not
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| 358 | apply to code that was developed with the Qt Open Source Edition
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| 359 | prior to the agreement. Any software developed with Qt
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| 360 | without a commercial license agreement must be released as
|
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| 361 | free/open source software.
|
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| 362 | <p> <hr>
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| 363 | <h2> Questions about Open Source Software Licensing
|
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| 364 | </h2>
|
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| 365 | <a name="5"></a><p> <hr width="30%">
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| 366 | <h3> I just want to run KDE and other Qt-based software on my
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| 367 | machine. Can I do that with the Open Source Edition?
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| 368 | </h3>
|
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| 369 | <a name="5-1"></a><p> Yes. You may use the Qt Open Source Edition for running applications,
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| 370 | both at home and at work, without restrictions.
|
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| 371 | <p> <hr width="30%">
|
|---|
| 372 | <h3> I want to put Qt, and applications that use it, on a CD-ROM or on
|
|---|
| 373 | a web site. Can I do that with the Open Source Edition?
|
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| 374 | </h3>
|
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| 375 | <a name="5-2"></a><p> Yes. You may copy and redistribute the Qt Open Source Edition, both
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| 376 | at home and at work, without restrictions.
|
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| 377 | <p> <hr width="30%">
|
|---|
| 378 | <h3> Can I make software with the Qt Open Source Edition and release it under
|
|---|
| 379 | the GNU GPL, BSD, or Artistic license?
|
|---|
| 380 | </h3>
|
|---|
| 381 | <a name="5-3"></a><p> Yes. The GNU GPL, GPL-compatible licenses, or any other
|
|---|
| 382 | approved open source license will do. The FSF.org and
|
|---|
| 383 | OpenSource.org web sites list approved software licenses.
|
|---|
| 384 | <p> <hr width="30%">
|
|---|
| 385 | <h3> I don't want to give away my source code. What do I do?
|
|---|
| 386 | </h3>
|
|---|
| 387 | <a name="5-4"></a><p> You need to buy a commercial Qt license.
|
|---|
| 388 | <p> <hr width="30%">
|
|---|
| 389 | <h3> Is software based on the Qt Open Source Edition really free? Does it
|
|---|
| 390 | carry any Trolltech-specific license restrictions?
|
|---|
| 391 | </h3>
|
|---|
| 392 | <a name="5-5"></a><p> Yes, it really is free. This is because the Qt Open Source Edition
|
|---|
| 393 | uses the GNU GPL, which forbids the imposition of any license
|
|---|
| 394 | restrictions on software based on the Open Source Edition that would
|
|---|
| 395 | make it non-free. And no, there are no Trolltech-specific
|
|---|
| 396 | license restrictions on software produced using the Open Source
|
|---|
| 397 | Edition.
|
|---|
| 398 | <p> <hr width="30%">
|
|---|
| 399 | <h3> What if Trolltech stops releasing Open Source Editions of Qt?
|
|---|
| 400 | </h3>
|
|---|
| 401 | <a name="5-6"></a><p> We have absolutely no intention of doing that. Together with
|
|---|
| 402 | the K Desktop Environment project, we have set up the KDE Free
|
|---|
| 403 | Qt Foundation (see
|
|---|
| 404 | <a href="http://www.kde.org/whatiskde/kdefreeqtfoundation.php">http://www.kde.org/whatiskde/kdefreeqtfoundation.php</a>) to
|
|---|
| 405 | legally guarantee the availability of Qt for free software
|
|---|
| 406 | development now and forever - even if circumstances beyound
|
|---|
| 407 | our control prevent us from producing new free editions.
|
|---|
| 408 | <p> <hr width="30%">
|
|---|
| 409 | <h3> Using the Open Source Edition, can I make non-free software for internal
|
|---|
| 410 | use in my company/organization?
|
|---|
| 411 | </h3>
|
|---|
| 412 | <a name="5-7"></a><p> No. Software developed with the Open Source Edition is always free
|
|---|
| 413 | software, i.e. it can only be distributed under a free
|
|---|
| 414 | software license. In particular, all the source code for all
|
|---|
| 415 | the modules your software is based on, regardless of whether
|
|---|
| 416 | they have been written by you or by others, must be free
|
|---|
| 417 | software. This is part of our commitment to the free software
|
|---|
| 418 | community, and enables those who contribute to the free
|
|---|
| 419 | software pool to do so without paying license fees.
|
|---|
| 420 | <p> Although it is possible to write free software for internal
|
|---|
| 421 | use, it is difficult to ensure that such software is used and
|
|---|
| 422 | distributed legally. For example, if your free software
|
|---|
| 423 | requires any modules that impose conditions on you that
|
|---|
| 424 | contradict the conditions of the GNU GPL, including, but not
|
|---|
| 425 | limited to, software patents, commercial license agreements,
|
|---|
| 426 | copyrighted interface definitions or any sort of
|
|---|
| 427 | non-disclosure agreement, then you cannot distribute it at
|
|---|
| 428 | all; hence it cannot be given to consultants, employees for
|
|---|
| 429 | their personal computers, subsidiaries, other divisions, or
|
|---|
| 430 | even to new owners.
|
|---|
| 431 | <p> Consequently we recommend using commercial licenses for all
|
|---|
| 432 | internal software development.
|
|---|
| 433 | <p> <hr width="30%">
|
|---|
| 434 | <h3> Is Qt Open Source Edition really free software in the GNU meaning of the
|
|---|
| 435 | word?
|
|---|
| 436 | </h3>
|
|---|
| 437 | <a name="5-8"></a><p> Yes - it is free software both as in "no cost" and as in
|
|---|
| 438 | "free speech". Even more, it is actually available under the
|
|---|
| 439 | terms of the GNU GPL. This means you can link GPL'ed software
|
|---|
| 440 | to it, and you can take code from Qt and put it into other
|
|---|
| 441 | GPL'ed software.
|
|---|
| 442 | <p> <hr width="30%">
|
|---|
| 443 | <h3> If the Open Source Edition is GNU GPL, aren't there license conflicts
|
|---|
| 444 | with incompatible open source licenses? How come people can even
|
|---|
| 445 | run commercial software like the Opera web browser with it?
|
|---|
| 446 | </h3>
|
|---|
| 447 | <a name="5-9"></a><p> If the Open Source Edition was licensed purely under the GNU GPL,
|
|---|
| 448 | there would be problems. However, as long as Qt-based
|
|---|
| 449 | software is either open source or was developed under a
|
|---|
| 450 | commercial license agreement with Trolltech, we grant
|
|---|
| 451 | permission to compile, link and run those programs with the
|
|---|
| 452 | Open Source Edition. This is written down in our second free software
|
|---|
| 453 | license, the QPL.
|
|---|
| 454 | <p> <hr width="30%">
|
|---|
| 455 | <h3> Doesn't such an en extra license in addition to the GNU GPL
|
|---|
| 456 | violate the terms of the GPL or at least make the whole package
|
|---|
| 457 | GPL-incompatible?
|
|---|
| 458 | </h3>
|
|---|
| 459 | <a name="5-10"></a><p> No, because those extra license terms give you rights in
|
|---|
| 460 | addition to those of the GNU GPL, including the right to
|
|---|
| 461 | remove those extra terms.
|
|---|
| 462 | <p> <hr width="30%">
|
|---|
| 463 | <h3> Why is Qt Open Source Edition not distributed under the GNU Lesser
|
|---|
| 464 | General Public License (LGPL)?
|
|---|
| 465 | </h3>
|
|---|
| 466 | <a name="5-11"></a><p> The LGPL is designed to "permit developers of non-free
|
|---|
| 467 | programs to use free libraries" (quote from the LGPL). In
|
|---|
| 468 | other words, if Qt Open Source Edition were LGPL'd, companies would
|
|---|
| 469 | not have to purchase our commercial editions in order to make
|
|---|
| 470 | commercial/proprietary software, they could just use the Open Source
|
|---|
| 471 | Edition, free of charge. That would mean Trolltech would not
|
|---|
| 472 | get the revenue necessary for improving and extending Qt.
|
|---|
| 473 | <p> Note also that the Free Software Foundation discourages the
|
|---|
| 474 | use of the LGPL.
|
|---|
| 475 | <p> <hr>
|
|---|
| 476 | <h2> Questions about other programming languages
|
|---|
| 477 | </h2>
|
|---|
| 478 | <a name="6"></a><p> <hr width="30%">
|
|---|
| 479 | <h3> Are there bindings to languages other than C++?
|
|---|
| 480 | </h3>
|
|---|
| 481 | <a name="6-1"></a><p> Yes there are, e.g. bindings to Perl (PerlQt) and Python
|
|---|
| 482 | (PyQt). These bindings were written by the open source
|
|---|
| 483 | community and are not supported by Trolltech.
|
|---|
| 484 | <p> <hr width="30%">
|
|---|
| 485 | <h3> Can I develop commercial applications with PerlQt or PyQt or other
|
|---|
| 486 | Qt wrappers?
|
|---|
| 487 | </h3>
|
|---|
| 488 | <a name="6-2"></a><p> Yes, if you have purchased a commercial license. The licensing
|
|---|
| 489 | conditions are the same whether you use the Qt API directly in
|
|---|
| 490 | C++, or you use it through some API wrapper in another
|
|---|
| 491 | programming language. All developers that write code
|
|---|
| 492 | containing calls to the Qt API (directly or through a wrapper)
|
|---|
| 493 | need Qt licenses.
|
|---|
| 494 | <p>
|
|---|
| 495 | <!-- eof -->
|
|---|
| 496 | <p><address><hr><div align=center>
|
|---|
| 497 | <table width=100% cellspacing=0 border=0><tr>
|
|---|
| 498 | <td>Copyright © 2007
|
|---|
| 499 | <a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
|
|---|
| 500 | <td align=right><div align=right>Qt 3.3.8</div>
|
|---|
| 501 | </table></div></address></body>
|
|---|
| 502 | </html>
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