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4<TITLE>wxWidgets 2 for Windows FAQ</TITLE>
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15<b>wxWidgets 2 for Windows FAQ</b>
16</font>
17</td>
18</tr>
19</table>
20
21<P>
22
23See also <a href="faq.htm">top-level FAQ page</a>.
24<hr>
25<h3>List of questions in this category</h3>
26<ul>
27<li><a href="#platforms">Which Windows platforms are supported?</a></li>
28<li><a href="#wince">What about Windows CE?</a></li>
29<li><a href="#winxp">What do I need to do for Windows XP?</a></li>
30<li><a href="#compilers">What compilers are supported?</a></li>
31<li><a href="#bestcompiler">Which is the best compiler to use with wxWidgets 2?</a></li>
32<li><a href="#unicode">Is Unicode supported?</a></li>
33<li><a href="#doublebyte">Does wxWidgets support double byte fonts (Chinese/Japanese/Korean etc.)?</a></li>
34<li><a href="#dll">Can you compile wxWidgets 2 as a DLL?</a></li>
35<li><a href="#exesize">How can I reduce executable size?</a></li>
36<li><a href="#mfc">Is wxWidgets compatible with MFC?</a></li>
37<li><a href="#setuph">Why do I get errors about setup.h not being found?</a></li>
38<li><a href="#asuffix">Why do I get errors about FooBarA when I only use FooBar in my program?</a></li>
39<li><a href="#newerrors">Why my code fails to compile with strange errors about new operator?</a></li>
40<li><a href="#mfcport">How do I port MFC applications to wxWidgets?</a></li>
41<li><a href="#crash">Why do I sometimes get bizarre crash problems using VC++ 5/6?</a></li>
42<li><a href="#makefiles">How are the wxWidgets makefiles edited under Windows?</a></li>
43<li><a href="#vcdebug">How do you use VC++&#39;s memory leak checking instead of that in wxWidgets?</a></li>
44<li><a href="#shortcutproblem">Why are menu hotkeys or shortcuts not working in my application?</a></li>
45<li><a href="#regconfig">Why can I not write to the HKLM part of the registry with wxRegConfig?</a></li>
46<li><a href="#access">Is MS Active Accessibility supported?</a></li>
47<li><a href="#dspfmt">Why does Visual C++ complain about corrupted project files?</a></li>
48<li><a href="#crtmismatch">Visual C++ gives errors about multiply defined symbols, what can I do?</a></li>
49<li><a href="#directx">Why do I get compilation errors when using wxWidgets with DirectShow?</a></li>
50<li><a href="#handlewm">How do I handle Windows messages in my wxWidgets program?</a></li>
51</ul>
52<hr>
53
54<h3><a name="platforms">Which Windows platforms are supported?</a></h3>
55
56wxWidgets 2 can be used to develop and deliver applications on Windows 3.1, Win32s,
57Windows 95, Windows 98, Windows NT, Windows 2000, and Windows XP. A Windows CE
58version is being looked into (see below).<P>
59
60wxWidgets 2 is designed to make use of WIN32 features and controls. However, unlike Microsoft,
61we have not forgotten users of 16-bit Windows. Most features
62work under Windows 3.1, including wxTreeCtrl and wxListCtrl using the generic implementation.
63However, don&#39;t expect very Windows-95-specific classes to work, such as wxTaskBarIcon. The wxRegConfig
64class doesn&#39;t work either because the Windows 3.1 registry is very simplistic. Check out the 16-bit
65makefiles to see what other files have been left out.
66<P>
6716-bit compilation is supported under Visual C++ 1.5, and Borland BC++ 4 to 5.
68<P>
69
70wxWidgets 2 for Windows will also compile on Unix with gcc using Wine from <a href="http://www.winehq.org" target=_top>WineHQ</a>.
71The resulting executables are Unix binaries that work with the Wine Windows API emulator.<P>
72
73You can also compile wxWidgets 2 for Windows on Unix with Cygwin or Mingw32, resulting
74in executables that will run on Windows. So in theory you could write your applications
75using wxGTK or wxMotif, then check/debug your wxWidgets for Windows
76programs with Wine, and finally produce an ix86 Windows executable using Cygwin/Mingw32,
77without ever needing a copy of Microsoft Windows. See the Technical Note on the Web site detailing cross-compilation.<P>
78
79<h3><a name="wince">What about Windows CE?</a></h3>
80
81This port is largely complete. For further information, see the <a href="http://www.wxwidgets.org/embedded.htm#wxwince">wxEmbedded</a> page.<P>
82
83<h3><a name="winxp">What do I need to do for Windows XP?</a></h3>
84
85In the same directory as you have your executable (e.g. foo.exe) you
86put a file called foo.exe.manifest in which you have something like
87the following:
88
89<pre>
90&lt;?xml version="1.0" encoding="UTF-8" standalone="yes"?&gt;
91&lt;assembly
92 xmlns="urn:schemas-microsoft-com:asm.v1"
93 manifestVersion="1.0"&gt;
94&lt;assemblyIdentity
95 processorArchitecture="x86"
96 version="5.1.0.0"
97 type="win32"
98 name="foo.exe"/&gt;
99 &lt;description&gt;Foo program&lt;/description&gt;
100 &lt;dependency&gt;
101 &lt;dependentAssembly&gt;
102 &lt;assemblyIdentity
103 type="win32"
104 name="Microsoft.Windows.Common-Controls"
105 version="6.0.0.0"
106 publicKeyToken="6595b64144ccf1df"
107 language="*"
108 processorArchitecture="x86"/&gt;
109 &lt;/dependentAssembly&gt;
110 &lt;/dependency&gt;
111&lt;/assembly&gt;
112</pre>
113
114If you want to add it to your application permanently,
115you can also include it in your .rc file using this
116line:<P>
117
118<PRE>
119 1 24 "winxp.manifest"
120</PRE>
121
122In wxWidgets 2.5, this will be in the wx/msw/wx.rc and
123so will happen automatically so long as you include wx.rc
124in your own .rc file.<P>
125
126For an explanation of this syntax, please see
127<a href="http://delphi.about.com/library/bluc/text/uc111601a.htm" target=_new>this
128article</a>.
129<P>
130
131<h3><a name="compilers">What compilers are supported?</a></h3>
132
133Please see the wxWidgets 2 for Windows install.txt file for up-to-date information, but
134currently the following are known to work:<P>
135
136<ul>
137<li>Visual C++ 1.5, 4.0, 5.0, 6.0, 7.0, 7.1
138<li>Borland C++ 4.5, 5.0, 5.5
139<li>Borland C++Builder 1.0, 3.0, X
140<li>Watcom C++ 10.6 (Win32), OpenWatcom 1.0
141<li>Cygwin (using configure)
142<li>Mingw32
143<li>MetroWerks CodeWarrior (many versions)
144<li>Digital Mars 8.34+
145</ul>
146<P>
147
148
149<h3><a name="bestcompiler">Which is the best compiler to use with wxWidgets 2?</a></h3>
150
151It&#39;s partly a matter of taste, but I (JACS) prefer Visual C++ since the debugger is very
152good, it&#39;s very stable, the documentation is extensive, and it generates small executables.
153Since project files are plain text, it&#39;s easy for me to generate appropriate project files
154for wxWidgets samples.<P>
155
156Borland C++ is fine - and very fast - but it&#39;s hard (impossible?) to use the debugger without using project files, and
157the debugger is nowhere near up to VC++&#39;s quality. The IDE isn&#39;t great.<P>
158
159C++Builder&#39;s power isn&#39;t really used with wxWidgets since it needs integration with its
160own class library (VCL). For wxWidgets, I&#39;ve only used it with makefiles, in which case
161it&#39;s almost identical to BC++ 5.0 (the same makefiles can be used).<P>
162
163You can&#39;t beat Cygwin&#39;s price (free), and you can debug adequately using gdb. However, it&#39;s
164quite slow to compile since it does not use precompiled headers.<P>
165
166CodeWarrior is cross-platform - you can debug and generate Windows executables from a Mac, but not
167the other way around I think - but the IDE is, to my mind, a bit primitive.<P>
168
169Watcom C++ is a little slow and the debugger is not really up to today&#39;s standards.<P>
170
171Among the free compilers the best choice seem to be Borland C++ command line
172tools and mingw32 (port of gcc to Win32). Both of them are supported by
173wxWidgets.
174
175<h3><a name="unicode">Is Unicode supported?</a></h3>
176
177Yes, Unicode is fully supported under Windows NT/2000 and there is limited
178support for it under Windows 9x using <a
179href="http://www.microsoft.com/globaldev/handson/dev/mslu_announce.mspx">MSLU</a>.
180<p>
181
182<h3><a name="doublebyte">Does wxWidgets support double byte fonts (Chinese/Japanese/Korean etc.)?</a></h3>
183
184For Japanese under Win2000, it seems that wxWidgets has no problems to work
185with double byte char sets (meaning DBCS, not Unicode). First you have to
186install Japanese support on your Win2K system and choose for ANSI translation
187<tt>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CodePage=932</tt>
188(default is 1252 for Western). Then you can see all the Japanese letters in
189wxWidgets applications.
190<p>
191
192<h3><a name="dll">Can you compile wxWidgets 2 as a DLL?</a></h3>
193
194Yes (using the Visual C++ or Borland C++ makefile), but be aware that distributing DLLs is a thorny issue
195and you may be better off compiling statically-linked applications, unless you&#39;re
196delivering a suite of separate programs, or you&#39;re compiling a lot of wxWidgets applications
197and have limited hard disk space.<P>
198
199With a DLL approach, and with different versions and configurations of wxWidgets
200needing to be catered for, the end user may end up with a host of large DLLs in his or her Windows system directory,
201negating the point of using DLLs. Of course, this is not a problem just associated with
202wxWidgets!
203<P>
204
205<h3><a name="exesize">How can I reduce executable size?</a></h3>
206
207You can compile wxWidgets as a DLL (see above, VC++/BC++ only at present). You should also
208compile your programs for release using non-debugging and space-optimisation options, but
209take with VC++ 5/6 space optimisation: it can sometimes cause problems.<P>
210
211If you want to distribute really small executables, you can
212use <a href="http://www.un4seen.com/petite/" target=_top>Petite</a>
213by Ian Luck. This nifty utility compresses Windows executables by around 50%, so your 500KB executable
214will shrink to a mere 250KB. With this sort of size, there is reduced incentive to
215use DLLs. Another good compression tool (probably better than Petite) is <a href="http://upx.sourceforge.net/" target=_top>UPX</a>.
216<P>
217
218Please do not be surprised if MinGW produces a statically-linked minimal executable of 1 MB. Firstly, gcc
219produces larger executables than some compilers. Secondly, this figure will
220include most of the overhead of wxWidgets, so as your application becomes more
221complex, the overhead becomes proportionally less significant. And thirdly, trading executable compactness
222for the enormous increase in productivity you get with wxWidgets is almost always well worth it.<P>
223
224If you have a really large executable compiled with MinGW (for example 20MB) then
225you need to configure wxWidgets to compile without debugging information: see
226docs/msw/install.txt for details. You may find that using configure instead
227of makefile.g95 is easier, particularly since you can maintain debug and
228release versions of the library simultaneously, in different directories.
229Also, run &#39;strip&#39; after linking to remove all traces of debug info.
230<P>
231
232<H3><a name="mfc">Is wxWidgets compatible with MFC?</a></H3>
233
234There is a sample which demonstrates MFC and wxWidgets code co-existing in the same
235application. However, don&#39;t expect to be able to enable wxWidgets windows with OLE-2
236functionality using MFC.<P>
237
238<H3><a name="setuph">Why do I get errors about setup.h not being found?</a></H3>
239
240When you build the wxWidgets library, setup.h is copied
241from include/wx/msw/setup.h to e.g. lib/mswd/wx/setup.h (the path
242depends on the configuration you&#39;re building). So you need to add
243this include path if building using the static Debug library:<P>
244
245lib/mswd<P>
246
247or if building the static Release library, lib/msw.<P>
248
249See also the <a href="http://wiki.wxwidgets.org/wiki.pl?Table_Of_Contents">wxWiki Contents</a>
250for more information.<P>
251
252
253<H3><a name="asuffix">Why do I get errors about FooBarA when I only use FooBar in my program?</H3>
254
255If you get errors like
256<p>
257<center>
258<tt>no matching function for call to &#39;wxDC::DrawTextA(const char[5], int,
259int)&#39;</tt>
260</center>
261<p>
262or similar ones for the other functions, i.e. the compiler error messages
263mention the function with the <tt>&#39;A&#39;</tt> suffix while you didn&#39;t
264use it in your code, the explanation is that you had included
265<tt>&#60;windows.h&#062;</tt> header which redefines many symbols to have such
266suffix (or <tt>&#39;W&#39;</tt> in the Unicode builds).
267
268<p>
269The fix is to either not include <tt>&#60;windows.h&#62;</tt> at all or include
270<tt>"wx/msw/winundef.h"</tt> immediately after it.
271
272<H3><a name="newerrors">Why my code fails to compile with strange errors about new operator?</a></H3>
273
274The most common cause of this problem is the memory debugging settings in
275<tt>wx/msw/setup.h</tt>. You have several choices:
276
277<ul>
278 <li> Either disable overloading the global operator new completely by
279 setting <tt>wxUSE_GLOBAL_MEMORY_OPERATORS</tt> and
280 <tt>wxUSE_DEBUG_NEW_ALWAYS</tt> to 0 in this file
281 <li> Or leave them on but do <tt>#undef new</tt> after including any
282 wxWidgets headers, like this the memory debugging will be still on
283 for wxWidgets sources but off for your own code
284</ul>
285
286Notice that IMHO the first solution is preferable for VC++ users who can use
287the <a href="#vcdebug">VC++ CRT memory debugging features</a> instead.
288
289<H3><a name="mfcport">How do I port MFC applications to wxWidgets?</a></H3>
290
291Set up your interface from scratch using wxWidgets (especially <a href="http://www.robeling.de" target=_top>wxDesigner</a>
292or <a href="http://www.anthemion.co.uk/dialogblocks/" target=_new>DialogBlocks</a> --
293it&#39;ll save you a <i>lot</i> of time) and when you have a shell prepared, you can start
294&#39;pouring in&#39; code from the MFC app, with appropriate
295modifications. This is the approach I have used, and I found
296it very satisfactory. A two-step process then - reproduce the bare
297interface first, then wire it up afterwards. That way you deal
298with each area of complexity separately. Don&#39;t try to think MFC
299and wxWidgets simultaneously from the beginning - it is easier to
300reproduce the initial UI by looking at the behaviour of the MFC
301app, not its code.
302
303<H3><a name="crash">Why do I sometimes get bizarre crash problems using VC++ 5/6?</a></H3>
304
305Some crash problems can be due to inconsistent compiler
306options (and of course this isn&#39;t limited to wxWidgets).
307If strange/weird/impossible things start to happen please
308check (dumping IDE project file as makefile and doing text comparison
309if necessary) that the project settings, especially the list of defined
310symbols, struct packing, etc. are exactly the same for all items in
311the project. After this, delete everything (including PCH) and recompile.<P>
312
313VC++ 5&#39;s optimization code seems to be broken and can
314cause problems: this can be seen when deleting an object Dialog
315Editor, in Release mode with optimizations on. If in doubt,
316switch off optimisations, although this will result in much
317larger executables. It seems possible that the library can be created with
318strong optimization, so long as the application is not strongly
319optimized. For example, in wxWidgets project, set to &#39;Minimum
320Size&#39;. In Dialog Editor project, set to &#39;Customize: Favor Small
321Code&#39; (and no others). This will then work.<P>
322
323<H3><a name="makefiles">How are the wxWidgets makefiles edited under Windows?</a></H3>
324
325wxWidgets 2.5.x and above uses Bakefile to generate makefiles, which
326is described in technical note 16 under docs/tech in your distribution.
327For 2.4.x, the following explanation applies.<P>
328
329As of wxWidgets 2.1, there is a new system written by Vadim Zeitlin, that
330generates the makefiles from templates using tmake.<P>
331
332Here are Vadim&#39;s notes:<P>
333
334<blockquote>
335To use these new makefiles, you don&#39;t need anything (but see below).
336However, you should NOT modify them because these files will be
337rewritten when I regenerate them using tmake the next time. So, if
338you find a problem with any of these makefiles (say, makefile.b32)
339you&#39;ll need to modify the corresponding template (b32.t in this
340example) and regenerate the makefile using tmake.<P>
341
342tmake can be found at
343<a href="http://www.troll.no/freebies/tmake.html" target=_new>www.troll.no/freebies/tmake.html</a>.
344It&#39;s a Perl5 program and so it needs Perl (doh). There is a binary for
345Windows (available from the same page), but I haven&#39;t used it, so
346I don&#39;t know if it works as flawlessly as "perl tmake" does (note
347for people knowing Perl: don&#39;t try to run tmake with -w, it won&#39;t
348do you any good). Using it extremely simple: to regenerate makefile.b32
349just go to distrib/msw/tmake and type<P>
350
351<pre>tmake -t b32 wxwin.pro -o ../../src/msw/makefile.b32</pre><P>
352
353The makefiles are untested - I don&#39;t have any of Borland, Watcom or
354Symantec and I don&#39;t have enough diskspace to recompile even with
355VC6 using makefiles. The new makefiles are as close as possible to the
356old ones, but not closer: in fact, there has been many strange things
357(should I say bugs?) in some of makefiles, some files were not compiled
358without any reason etc. Please test them and notify me about any problems.
359Better yet, modify the template files to generate the correct makefiles
360and check them in.<P>
361
362The templates are described in tmake ref manual (1-2 pages of text)
363and are quite simple. They do contain some Perl code, but my Perl is
364primitive (very C like) so it should be possible for anybody to make
365trivial modifications to it (I hope that only trivial modifications
366will be needed). I&#39;ve tagged the ol makefiles as MAKEFILES_WITHOUT_TMAKE
367in the cvs, so you can always retrieve them and compare the new ones,
368this will make it easier to solve the problems you might have.<P>
369
370Another important file is filelist.txt: it contains the list of all
371files to be compiled. Some of them are only compiled in 16/32 bit mode.
372Some other are only compiled with some compilers (others can&#39;t compile
373them) - all this info is contained in this file.<P>
374
375So now adding a new file to wxWidgets is as easy as modifying filelist.txt
376(and Makefile.ams for Unix ports) and regenerating the makefiles - no
377need to modify all files manually any more.<P>
378
379 Finally, there is also a file vc6.t which I use myself: this one
380generates a project file for VC++ 6.0 (I didn&#39;t create vc5.t because
381I don&#39;t need it and can&#39;t test it, but it should be trivial to create
382one from vc6.t - probably the only things to change would be the
383version number in the very beginning and the /Z option - VC5 doesn&#39;t
384support edit-and=continue). This is not an officially supported way
385of building wxWidgets (that is, nobody guarantees that it will work),
386but it has been very useful to me and I hope it will be also for
387others. To generate wxWidgets.dsp run<P>
388
389<pre>tmake -t vc6 wxwin.pro -o ../../wxWidgets.dsp</pre><P>
390
391Then just include this project in any workspace or open it from VC IDE
392and it will create a new workspace for you.<P>
393
394If all goes well, I&#39;m planning to create a template file for Makefile.ams
395under src/gtk and src/motif and also replace all makefiles in the samples
396subdirectories with the project files from which all the others will be
397generated. At least it will divide the number of files in samples
398directory by 10 (and the number of files to be maintained too).
399</blockquote>
400
401<P>
402
403<H3><a name="vcdebug">How do you use VC++&#39;s memory leak checking instead of that in wxWidgets?</a></H3>
404
405Vadim Zeitlin:
406
407<pre>
408On the VC++ level, it&#39;s just the matter of calling _CrtSetDbgFlag() in the very
409beginning of the program. In wxWidgets, this is done automatically when
410compiling with VC++ in debug mode unless wxUSE_GLOBAL_MEMORY_OPERATORS or
411__NO_VC_CRTDBG__ are defined - this check is done in wx/msw/msvcrt.h which
412is included from app.cpp which then calls wxCrtSetDbgFlag() without any
413ifdefs.
414
415This works quite well: at the end of the program, all leaked blocks with their
416malloc count are shown. This number (malloc count) can be used to determine
417where exactly the object was allocated: for this it&#39;s enough to set the variable
418_crtBreakAlloc (look in VC98\crt\srs\dbgheap.c line 326) to this number and
419a breakpoint will be triggered when the block with this number is allocated.
420
421For simple situations it works like a charm. For something more complicated
422like reading uninitialized memory a specialized tool is probably better...
423
424Regards,
425VZ
426</pre>
427
428<P>
429
430<H3><a name="shortcutproblem">Why are menu hotkeys or shortcuts not working in my application?</a></H3>
431
432This can happen if you have a child window intercepting EVT_CHAR events and swallowing
433all keyboard input. You should ensure that event.Skip() is called for all input that
434isn&#39;used by the event handler.<P>
435
436It can also happen if you append the submenu to the parent
437menu {\it before} you have added your menu items. Do the append {\it after} adding
438your items, or accelerators may not be registered properly.<P>
439
440<H3><a name="#regconfig">Why can I not write to the HKLM part of the registry with wxRegConfig?</a></H3>
441
442Currently this is not possible because the wxConfig family of classes is
443supposed to deal with per-user application configuration data, and HKLM is
444only supposed to be writeable by a user with Administrator privileges. In theory,
445only installers should write to HKLM. This is still a point debated by the
446wxWidgets developers. There are at least two ways to work around it if you really
447need to write to HKLM.<P>
448
449First, you can use wxRegKey directly, for example:
450
451<pre>
452 wxRegKey regKey;
453
454 wxString idName(wxT("HKEY_LOCAL_MACHINE\\SOFTWARE\\My Company\\My Product\\Stuff\\"));
455 idName += packid;
456
457 regKey.SetName(idName);
458
459 {
460 wxLogNull dummy;
461 if (!regKey.Create())
462 {
463 idName = wxT("HKEY_CURRENT_USER\\SOFTWARE\\My Company\\My Product\\Stuff\\");
464 idName += packid;
465 regKey.SetName(idName);
466 if (!regKey.Create())
467 return FALSE;
468 }
469 }
470
471 if (!regKey.SetValue(wxT("THING"), (long) thing)) err += 1;
472
473 regKey.Close();
474
475</pre>
476
477Or, you can employ this trick suggested by Istvan Kovacs:
478
479<pre>
480class myGlobalConfig : public wxConfig
481{
482 myGlobalConfig() :
483 wxConfig ("myApp", "myCompany", "", "", wxCONFIG_USE_GLOBAL_FILE)
484{};
485 bool Write(const wxString& key, const wxString& value);
486}
487
488bool myGlobalConfig::Write (const wxString& key, const wxString& value)
489{
490 wxString path = wxString ("SOFTWARE\\myCompany\\myApp\\") + wxPathOnly(key);
491 wxString new_path = path.Replace ("/", "\\", true);
492 wxString new_key = wxFileNameFromPath (key);
493 LocalKey().SetName (wxRegKey::HKLM, path);
494 return wxConfig::Write (new_key, value);
495}
496</pre>
497
498<H3><a name="#access">Is MS Active Accessibility supported?</a></H3>
499
500This is being worked on. Please see <a href="http://www.wxwidgets.org/access.htm">this page</a>
501for the current status.
502
503<P>
504
505
506<h3><a name="#dspfmt">Why does Visual C++ complain about corrupted project files?</a></h3>
507
508If you have downloaded the wxWidgets sources from the cvs using a Unix cvs
509client or downloaded a daily snapshot in <tt>.tar.gz</tt> format, it is likely
510that the project files have Unix line endings (LF) instead of the DOS ones (CR
511LF). However all versions of Visual C++ up to and including 7.1 can only open
512the files with the DOS line endings, so you must transform the files to this
513format using any of the thousands ways to do it.
514<p>
515Of course, another possibility is to always use only the Windows cvs client
516and to avoid this problem completely.
517<p>
518
519<h3><a name="#crtmismatch">Visual C++ gives errors about multiply defined symbols, what can I do?</a></h3>
520
521If you get errors like this
522
523<pre>
524MSVCRTD.lib(MSVCRTD.dll) : error LNK2005: _xxxxxx already defined in LIBCD.lib(yyyyy.obj)
525</pre>
526
527when linking your project, this means that you used different versions of CRT
528(C Run-Time) library for wxWindows (or possibly another library) and the main
529project. Visual C++ provides static or dynamic and multithread safe or not
530versions of CRT for each of debug and release builds, for a total of 8
531libraries. You can choose among them by going to the "Code generation"
532page/subitem of the "C++" tab/item in the project proprieties dialog in VC6/7.
533<p>
534To avoid problems, you <strong>must</strong> use the same one for all
535components of your project. wxWindows uses multithread safe DLL version of the
536CRT which is a good choice but may be problematic when distributing your
537applications if you don&#39;t include the CRT DLL in your installation -- in this
538case you may decide to switch to using a static CRT version. If you build with
539<tt>wxUSE_THREADS == 0</tt> you may also use the non MT-safe version as it is
540slightly smaller and faster.
541<p>
542But the most important thing is to use the <strong>same</strong> CRT setting for
543all components of your project.
544
545<h3><a name="#directx">Why do I get compilation erros when using wxWidgets with DirectShow?</a></h3>
546
547If you get errors when including Microsoft DirectShow or DirectDraw headers,
548the following message from Peter Whaite could help:
549<blockquote>
550&gt; This causes compilation errors within DirectShow:
551&gt;
552&gt; wxutil.h(125) : error C2065: &#39;EXECUTE_ASSERT&#39; : undeclared identifier
553&gt; amfilter.h(1099) : error C2065: &#39;ASSERT&#39; : undeclared identifier
554
555The reason for this is that __WXDEBUG__ is also used by the DXSDK (9.0
556in my case) to &#39;#pragma once&#39; the contents of
557DXSDK/Samples/C++/DirectShow/BaseClasses/wxdebug.h. So if __WXDEBUG__
558is defined, then wxdebug.h doesn&#39;t get included, and the assert macros
559don&#39;t get defined. You have to #undef __WXDEBUG__ before including the
560directshow baseclass&#39;s &lt;streams.h&gt;.
561</blockquote>
562
563
564<h3><a name="#handlewm">How do I handle Windows messages in my wxWidgets program?</a></h3>
565
566To handle a Windows message you need to override a virtual
567<tt>MSWWindowProc()</tt> method in a wxWindow-derived class. You should then
568test if <tt>nMsg</tt> parameter is the message you need to process and perform
569the necessary action if it is or call the base class method otherwise.
570
571
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