Currently, the Qt Reference Documentation is not shipped with the OS/2 version of the Qt Toolkit (it will be done later).
You can view it online using this link: http://doc.trolltech.com/3.3/index.html.
The OS/2 version of the Qt Library is not yet complete. Some features are still under development and there are some known bugs. They are briefly described below.
| 1 | Drag & Drop ( QT_NO_DRAGANDDROPis constantly
        defined for now) | 
| 2 | OS/2 widget style (a native look and feel of buttons, combo boxes and other common widgets) | 
| 3 | Printing support ( QPrinterclass is absent,QT_NO_PRINTERis constantly defined for now) | 
| 4 | Process management ( QProcess class is absent) | 
| 5 | Audio support ( QSoundclass) | 
| 6 | sql module ( QSqlclass and friends) | 
| 7 | table module ( QTableclass, depends only
        on Drag & Drop) | 
| 8 | iconview module ( QIconViewclass, depends
        only on Drag & Drop) | 
| 9 | canvas module ( QCanvasand friends) | 
| 10 | OpenGL module ( QGLclass and friends) | 
| 11 | Plugin support | 
| 12 | Qt Designer tool (depends only on Drag & Drop) | 
| 13 | Qt Linguist tool (depends only on Drag & Drop) | 
| 14 | Qt Assistant tool (depends only on Drag & Drop) | 
| 1 | Unicode is not fully supported in GUI, to the effect that only the symbols from the current (system) 8-bit charset can appear in widgets and when drawing text. | 
| 2 | Alpha blending for pixmaps is not yet implemented
        [ themesexample]. | 
| 3 | Complex text transformations (rotation etc.) don't work correctly
        with the FreeType2 rendering engine. Most likely a bug or a limitation
        of FreeType2 [ xformexample]. | 
| 4 | Text rotation to values greater than 90 degrees clockwise doesn't
        work with truetype fonts and the standard TTF rendering engine. This
        seems like an OS/2 bug [ xformexample]. | 
| 5 | Stay-on-top is not supported system-wide. | 
The GNUMAKE backend generates makefiles for the GNU Make utility from qmake's project files. A separate generator became necessary because the previously used MINGW generator has some problems and limitations that make it impossible to generate correct makefiles in several situations. This new generator is primarily intended to be used with GNU Make under OS/2, but theoretically can be used on any platform after some modifications. However, its usage under other platforms is not tested and not supported.
The GNUMAKE backend was initially based on the existing MINGW backend, so here is the list of its differences and improvements comparing to the MINGW backend:
1. QMAKE_LINK_OBJECT_MAX,
    QMAKE_LINK_OBJECT_SCRIPT,
    QMAKE_LINK_OBJMOC_SCRIPT are no longer supported, since the
    OS/2 version of GNU LD (linker) seems not to support object
    link scripts. The OS/2 CMD.EXE command line length limitation (1024 chars)
    is worked around in a different way (see the
    \mkspecs\os2-g++\qmake.conf if interested).
2. Added new qmake varibales QMAKE_RUN_LINK and
    QMAKE_RUN_LIB (intended to be used in qmake.conf) to
    explicitly specify the command to execute the linker and the librarian,
    respectively. These variables are optional and have the following
    defaults:
$(LINK) $(LFLAGS) -o $(TARGET) $(DEF_FILE) $(OBJECTS) $(OBJMOC) $(LIBS) $(LIB) $(TARGET) $(OBJECTS) $(OBJMOC)
3. QMAKE_EXTRA_WIN_COMPILERS and
    QMAKE_EXTRA_WIN_TARGETS are renamed to
    QMAKE_EXTRA_COMPILERS and QMAKE_EXTRA_TARGETS
    respectively, for clarity.
4. Leaving QMAKE_LIBS_QT_ENTRY empty does not produce a
    qmake warning any more.
5. Added the new qmake variable QMAKE_RUN_IMPLIB used to
    produce the import library when the target is the dynamic link library. It
    is expected that this variable specifies the output import library name
    with the $(TARGET_IMPLIB) macro, which is defined by qmake as
    the project's target dll full basename with the .lib
    extension.
6. Added new qmake variables QMAKE_RUN_GENDEF and
    QMAKE_GENDEF_DEPS. They are intended to generate a
    .def file containing a list of DLL exports when the target is
    the dynamic link library (i.e. when TEMPLATE = lib and
    CONFIG contains dll) and the
    DEF_FILE variable is empty or not specified in the project
    file. In this case, the DEF_FILE macro is defined by qmake as
    the project's target full basename with the .def extension.
    QMAKE_RUN_GENDEF is the command to generate this
    DEF_FILE (its output must go to $(DEF_FILE)).
    QMAKE_GENDEF_DEPS is the list of dependencies for the
    DEF_FILE.
7. Empty OBJECTS_DIR and MOC_DIR qmake
    variables do not cause GNU Make to print warnings any more.
8. Fixed the dist makefile target: the generated zip didn't have the name (only extension).
9. Commands for custom (user defined) targets and for extra compilers
    (i.e. values of <my_target>.commands variables) are now
    splitted at ' ;; ' sequences (a double semicolon
    surrounded by single spaces) and placed to separate lines in the makefile.
    For example, the definition
    '<my_target>.command = c1 ;; c2'
    will apperar as follows:
<my_target>: <my_target_deps>
    c1
    c2
    10. Added new qmake variables QMAKE_QUIET_CLEAN and
    QMAKE_IF_FILE_EXISTS. QMAKE_QUIET_CLEAN is
    similar QMAKE_CLEAN, but adds
    $(QMAKE_IF_FILE_EXISTS) to the beginning of each
    $(DEL_FILE) statement to delete a file only if it exists (to
    avoid system warnings).
11. Object files are no more forced to have the .o
    extension. The standard qmake QMAKE_EXT_OBJ variable is used
    instead (by default, on OS/2 it equals to .obj).
    QMAKE_EXT_CPP variable is regarded as well.
12. Library files now have the .lib extension (instead of .a), and the lib... prefix is no more prepended.
13. Added new QMAKE_CFLAGS_INCDIR,
    QMAKE_LFLAGS_LIBDIR, QMAKE_LFLAGS_LIB qmake
    variables to make it possible to customize the coorresponding flags (i.e.,
    -I, -L and -l, as for GCC) in the
    .conf file.
14. Added new QMAKE_LIBS_QT_DLL and
    QMAKE_LIBS_QT_THREAD_DLL qmake variables to specify the list
    of libraries required when the application is linked against the DLL
    version of Qt, separately from the list of libraries required for linking
    against the static Qt library.
15. The QMAKESPECDIR variable is defined in the generated
    makefile and points to the directory where a qmake.conf file
    being used was read from.
16. Added new qmake variables DEF_FILE_TEMPLATE and
    DEF_FILE_MAP. When the target is the dynamic link library and
    DEF_FILE is not defined in the project file, these
    variables (when defined) go to the generated makefile w/o any changes.
    They are also appended (as GNU make variables) to the contents of the
    QMAKE_GENDEF_DEPS variable (see 6).
    DEF_FILE_TEMPLATE is intended to point to an existing
    template for a .def file. DEF_FILE_MAP should
    point to an existing file used to store ordinals assigned to exported
    symbols (to make assignments persistent from build to build). The backend
    itself doesn't use these variables, they are used only to pass the
    information from the project file to the generated makefile. It is the
    responsibility of the .conf file to implement the described
    functionality.
17. Objects defining custom targets got the .extradeps
    attribute. This attrubute allows to specify additional target dependencies
    that are not followed by commands. That is, if you have the following
    extra target definition:
my_target.target = somefile my_target.depends = anotherfile my_target.extradeps = export SOMETHING = something my_target.commands = coolcmd > $$my_target.target
you'll get in the generated makefile:
somefile : export SOMETHING = something
somefile : anotherfile
    coolcmd > somefile
    Note that if you two or more additional dependencies each placed on a
    separate line, you can separate them using ' ;; ' (a
    double semicolon surrounded by single spaces) in the definition of the
    .extradeps attribute.