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wxMSW FAQ (Windows)

See also top-level FAQ page.


List of questions in this category


Which Windows platforms are supported?

wxWidgets can be used to develop and deliver applications on Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, and Windows Vista. A Windows CE port is also available (see below).

16-bit compilation is only supported for wxWidgets 2.4 and previous versions, using Visual C++ 1.5 and Borland BC++ 4 to 5.

wxWidgets for Windows will also compile on Unix with gcc using Wine from WineHQ. The resulting executables are Unix binaries that work with the Wine Windows API emulator.

You can also compile wxWidgets for Windows on Unix with Cygwin or Mingw32, resulting in executables that will run on Windows. So in theory you could write your applications using wxGTK or wxMotif, then check/debug your wxWidgets for Windows programs with Wine, and finally produce an ix86 Windows executable using Cygwin/Mingw32, without ever needing a copy of Microsoft Windows. See the Technical Note on the Web site detailing cross-compilation.

What about Windows CE?

This port supports Pocket PC 2002/2003 and MS Smartphone 2002/2003, using Embedded Visual C++ 3 or 4. For further information, see the wxMSW section in the wxWidgets Reference Manual, and also the wxEmbedded page.

What do I need to do for Windows XP?

From wxWidgets 2.5, the XP manifest is included in wx/msw/wx.rc and so your application will be themed automatically so long as you include wx.rc in your own .rc file.

For versions of wxWidgets below 2.5, you need to provide the manifest explicitly, as follows.

In the same directory as you have your executable (e.g. foo.exe) you put a file called foo.exe.manifest in which you have something like the following:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly
   xmlns="urn:schemas-microsoft-com:asm.v1"
   manifestVersion="1.0">
<assemblyIdentity
    processorArchitecture="x86"
    version="5.1.0.0"
    type="win32"
    name="foo.exe"/>
    <description>Foo program</description>
    <dependency>
    <dependentAssembly>
    <assemblyIdentity
         type="win32"
         name="Microsoft.Windows.Common-Controls"
         version="6.0.0.0"
         publicKeyToken="6595b64144ccf1df"
         language="*"
         processorArchitecture="x86"/>
    </dependentAssembly>
    </dependency>
</assembly>
If you want to add it to your application permanently, you can also include it in your .rc file using this line:

  1 24 "winxp.manifest"
For an explanation of this syntax, please see this article.

What compilers are supported?

Please see the wxWidgets for Windows install.txt file for up-to-date information, but currently the following are known to work:

  • Visual C++ 1.5, 4.0, 5.0, 6.0, 7.0, 7.1, 8.0
  • Borland C++ 4.5, 5.0, 5.5
  • Borland C++Builder 1.0, 3.0, X
  • Watcom C++ 10.6 (Win32), OpenWatcom 1.0
  • Cygwin (using configure)
  • Mingw32
  • MetroWerks CodeWarrior (many versions)
  • Digital Mars 8.34+

Which is the best compiler to use with wxWidgets?

It's partly a matter of taste, but some people prefer Visual C++ since the debugger is very good, it's very stable, the documentation is extensive, and it generates small executables. Since project files are plain text, it's easy for me to generate appropriate project files for wxWidgets samples.

Borland C++ is fine - and very fast - but it's hard (impossible?) to use the debugger without using project files, and the debugger is nowhere near up to VC++'s quality. The IDE isn't great.

C++Builder's power isn't really used with wxWidgets since it needs integration with its own class library (VCL). For wxWidgets, I've only used it with makefiles, in which case it's almost identical to BC++ 5.0 (the same makefiles can be used).

You can't beat Cygwin's price (free), and you can debug adequately using gdb. However, it's quite slow to compile since it does not use precompiled headers.

CodeWarrior is cross-platform - you can debug and generate Windows executables from a Mac, but not the other way around I think - but the IDE is, to my mind, a bit primitive.

Watcom C++ is a little slow and the debugger is not really up to today's standards.

Among the free compilers the best choice seem to be Borland C++ command line tools and mingw32 (port of gcc to Win32). Both of them are supported by wxWidgets. However BC++ has trouble compiling large executables statically, so you need to dynamically link the wxWidgets libraries.

Is Unicode supported?

Yes, Unicode is fully supported under Windows NT/2000 and there is limited support for it under Windows 9x using MSLU.

Does wxWidgets support double byte fonts (Chinese/Japanese/Korean etc.)?

For Japanese under Win2000, it seems that wxWidgets has no problems working with double byte char sets (meaning DBCS, not Unicode). First you have to install Japanese support on your Win2K system and choose for ANSI translation HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CodePage=932 (default is 1252 for Western). Then you can see all the Japanese letters in wxWidgets applications.

Can you compile wxWidgets as a DLL?

Yes (using the Visual C++ or Borland C++ makefile), but be aware that distributing DLLs is a thorny issue and you may be better off compiling statically-linked applications, unless you're delivering a suite of separate programs, or you're compiling a lot of wxWidgets applications and have limited hard disk space.

With a DLL approach, and with different versions and configurations of wxWidgets needing to be catered for, the end user may end up with a host of large DLLs in his or her Windows system directory, negating the point of using DLLs. Of course, this is not a problem just associated with wxWidgets!

How can I reduce executable size?

You can compile wxWidgets as a DLL (see above, VC++/BC++ only at present). You should also compile your programs for release using non-debugging and space-optimisation options, but take with VC++ 5/6 space optimisation: it can sometimes cause problems.

If you want to distribute really small executables, you can use Petite by Ian Luck. This nifty utility compresses Windows executables by around 50%, so your 500KB executable will shrink to a mere 250KB. With this sort of size, there is reduced incentive to use DLLs. Another good compression tool (probably better than Petite) is UPX.

Please do not be surprised if MinGW produces a statically-linked minimal executable of 1 MB. Firstly, gcc produces larger executables than some compilers. Secondly, this figure will include most of the overhead of wxWidgets, so as your application becomes more complex, the overhead becomes proportionally less significant. And thirdly, trading executable compactness for the enormous increase in productivity you get with wxWidgets is almost always well worth it.

If you have a really large executable compiled with MinGW (for example 20MB) then you need to configure wxWidgets to compile without debugging information: see docs/msw/install.txt for details. You may find that using configure instead of makefile.g95 is easier, particularly since you can maintain debug and release versions of the library simultaneously, in different directories. Also, run 'strip' after linking to remove all traces of debug info.

Is wxWidgets compatible with MFC?

There is a sample which demonstrates MFC and wxWidgets code co-existing in the same application. However, don't expect to be able to enable wxWidgets windows with OLE-2 functionality using MFC.

Why do I get errors about setup.h not being found?

When you build the wxWidgets library, setup.h is copied from include/wx/msw/setup.h to e.g. lib/vc_msw/mswd/wx/setup.h (the path depends on the configuration you're building). So you need to add this include path if building using the static Debug library:

lib/vc_lib/mswd

or if building the static Release library, lib/vc_lib/msw.

See also the wxWiki Contents for more information.

Why do I get errors about FooBarA when I only use FooBar in my program?

If you get errors like

no matching function for call to 'wxDC::DrawTextA(const char[5], int, int)'

or similar ones for the other functions, i.e. the compiler error messages mention the function with the 'A' suffix while you didn't use it in your code, the explanation is that you had included <windows.h> header which redefines many symbols to have such suffix (or 'W' in the Unicode builds).

The fix is to either not include <windows.h> at all or include "wx/msw/winundef.h" immediately after it.

Why my code fails to compile with strange errors about new operator?

The most common cause of this problem is the memory debugging settings in wx/msw/setup.h. You have several choices:
  • Either disable overloading the global operator new completely by setting wxUSE_GLOBAL_MEMORY_OPERATORS and wxUSE_DEBUG_NEW_ALWAYS to 0 in this file
  • Or leave them on but do #undef new after including any wxWidgets headers, like this the memory debugging will be still on for wxWidgets sources but off for your own code
Notice that IMHO the first solution is preferable for VC++ users who can use the VC++ CRT memory debugging features instead.

How do I port MFC applications to wxWidgets?

Set up your interface from scratch using wxWidgets (especially wxDesigner or DialogBlocks -- it'll save you a lot of time) and when you have a shell prepared, you can start 'pouring in' code from the MFC app, with appropriate modifications. This is the approach I have used, and I found it very satisfactory. A two-step process then - reproduce the bare interface first, then wire it up afterwards. That way you deal with each area of complexity separately. Don't try to think MFC and wxWidgets simultaneously from the beginning - it is easier to reproduce the initial UI by looking at the behaviour of the MFC app, not its code.

Why do I sometimes get bizarre crash problems using VC++ 5/6?

Some crash problems can be due to inconsistent compiler options (and of course this isn't limited to wxWidgets). If strange/weird/impossible things start to happen please check (dumping IDE project file as makefile and doing text comparison if necessary) that the project settings, especially the list of defined symbols, struct packing, etc. are exactly the same for all items in the project. After this, delete everything (including PCH) and recompile.

VC++ 5's optimization code seems to be broken and can cause problems: this can be seen when deleting an object Dialog Editor, in Release mode with optimizations on. If in doubt, switch off optimisations, although this will result in much larger executables. It seems possible that the library can be created with strong optimization, so long as the application is not strongly optimized. For example, in wxWidgets project, set to 'Minimum Size'. In Dialog Editor project, set to 'Customize: Favor Small Code' (and no others). This will then work.

Why are menu hotkeys or shortcuts not working in my application?

This can happen if you have a child window intercepting EVT_CHAR events and swallowing all keyboard input. You should ensure that event.Skip() is called for all input that isn't used by the event handler.

It can also happen if you append the submenu to the parent menu before you have added your menu items. Do the append after adding your items, or accelerators may not be registered properly.

Why can I not write to the HKLM part of the registry with wxRegConfig?

Currently this is not possible because the wxConfig family of classes is supposed to deal with per-user application configuration data, and HKLM is only supposed to be writeable by a user with Administrator privileges. In theory, only installers should write to HKLM. This is still a point debated by the wxWidgets developers. There are at least two ways to work around it if you really need to write to HKLM.

First, you can use wxRegKey directly, for example:

    wxRegKey regKey;

    wxString idName(wxT("HKEY_LOCAL_MACHINE\\SOFTWARE\\My Company\\My Product\\Stuff\\"));
    idName += packid;

    regKey.SetName(idName);

    {
        wxLogNull dummy;
        if (!regKey.Create())
        {
            idName = wxT("HKEY_CURRENT_USER\\SOFTWARE\\My Company\\My Product\\Stuff\\");
            idName += packid;
            regKey.SetName(idName);
            if (!regKey.Create())
                return FALSE;
        }
    }

    if (!regKey.SetValue(wxT("THING"), (long) thing)) err += 1;

    regKey.Close();

Or, you can employ this trick suggested by Istvan Kovacs:
class myGlobalConfig : public wxConfig
{
    myGlobalConfig() :
        wxConfig ("myApp", "myCompany", "", "", wxCONFIG_USE_GLOBAL_FILE)
{};
    bool Write(const wxString& key, const wxString& value);
}

bool myGlobalConfig::Write (const wxString& key, const wxString& value)
{
    wxString path = wxString ("SOFTWARE\\myCompany\\myApp\\") + wxPathOnly(key);
    wxString new_path = path.Replace ("/", "\\", true);
    wxString new_key = wxFileNameFromPath (key);
    LocalKey().SetName (wxRegKey::HKLM, path);
    return wxConfig::Write (new_key, value);
}

Is MS Active Accessibility supported?

This is being worked on. Please see this page for the current status.

Why does Visual C++ complain about corrupted project files?

If you have downloaded the wxWidgets sources from the cvs using a Unix cvs client or downloaded a daily snapshot in .tar.gz format, it is likely that the project files have Unix line endings (LF) instead of the DOS ones (CR LF). However all versions of Visual C++ up to and including 7.1 can only open the files with the DOS line endings, so you must transform the files to this format using any of the thousands ways to do it.

Of course, another possibility is to always use only the Windows cvs client and to avoid this problem completely.

Visual C++ gives errors about multiply defined symbols, what can I do?

If you get errors like this
MSVCRTD.lib(MSVCRTD.dll) : error LNK2005: _xxxxxx already defined in LIBCD.lib(yyyyy.obj)
when linking your project, this means that you used different versions of CRT (C Run-Time) library for wxWindows (or possibly another library) and the main project. Visual C++ provides static or dynamic and multithread safe or not versions of CRT for each of debug and release builds, for a total of 8 libraries. You can choose among them by going to the "Code generation" page/subitem of the "C++" tab/item in the project proprieties dialog in VC6/7.

To avoid problems, you must use the same one for all components of your project. wxWindows uses multithread safe DLL version of the CRT which is a good choice but may be problematic when distributing your applications if you don't include the CRT DLL in your installation -- in this case you may decide to switch to using a static CRT version. If you build with wxUSE_THREADS == 0 you may also use the non MT-safe version as it is slightly smaller and faster.

But the most important thing is to use the same CRT setting for all components of your project.

Why do I get compilation errors when using wxWidgets with DirectShow?

If you get errors when including Microsoft DirectShow or DirectDraw headers, the following message from Peter Whaite could help:
> This causes compilation errors within DirectShow:
>
> wxutil.h(125) : error C2065: 'EXECUTE_ASSERT' : undeclared identifier
> amfilter.h(1099) : error C2065: 'ASSERT' : undeclared identifier

The reason for this is that __WXDEBUG__ is also used by the DXSDK (9.0
in my case) to '#pragma once' the contents of
DXSDK/Samples/C++/DirectShow/BaseClasses/wxdebug.h.  So if __WXDEBUG__
is defined, then wxdebug.h doesn't get included, and the assert macros
don't get defined.  You have to #undef __WXDEBUG__ before including the
directshow baseclass's <streams.h>.

How to get HWND of a wxWindow object?

If you need to interface with native Windows code, you may use wxWindow::GetHWND() method whose result can be cast to HWND.

How do I handle Windows messages in my wxWidgets program?

To handle a Windows message you need to override a virtual MSWWindowProc() method in a wxWindow-derived class. You should then test if nMsg parameter is the message you need to process and perform the necessary action if it is or call the base class method otherwise.
 
 

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