1 2<HTML> 3 4<HEAD> 5<TITLE>wxWidgets for Windows FAQ</TITLE> 6</HEAD> 7 8<BODY BGCOLOR=#FFFFFF TEXT=#000000 VLINK="#00376A" LINK="#00529C" ALINK="#313063"> 9 10<font face="Arial, Lucida Sans, Helvetica"> 11 12<table width=100% border=0 cellpadding=3 cellspacing=0> 13<tr> 14<td bgcolor="#004080" align=left height=24 background="images/bluetitlegradient.gif"> 15<font size=+1 face="Arial, Lucida Sans, Helvetica" color="#FFFFFF"> 16<b>wxWidgets for Windows FAQ</b> 17</font> 18</td> 19</tr> 20</table> 21 22<P> 23 24See also <a href="faq.htm">top-level FAQ page</a>. 25<hr> 26<h3>List of questions in this category</h3> 27<ul> 28<li><a href="#platforms">Which Windows platforms are supported?</a></li> 29<li><a href="#wince">What about Windows CE?</a></li> 30<li><a href="#winxp">What do I need to do for Windows XP?</a></li> 31<li><a href="#compilers">What compilers are supported?</a></li> 32<li><a href="#bestcompiler">Which is the best compiler to use with wxWidgets?</a></li> 33<li><a href="#unicode">Is Unicode supported?</a></li> 34<li><a href="#doublebyte">Does wxWidgets support double byte fonts (Chinese/Japanese/Korean etc.)?</a></li> 35<li><a href="#dll">Can you compile wxWidgets as a DLL?</a></li> 36<li><a href="#exesize">How can I reduce executable size?</a></li> 37<li><a href="#mfc">Is wxWidgets compatible with MFC?</a></li> 38<li><a href="#setuph">Why do I get errors about setup.h not being found?</a></li> 39<li><a href="#asuffix">Why do I get errors about FooBarA when I only use FooBar in my program?</a></li> 40<li><a href="#newerrors">Why my code fails to compile with strange errors about new operator?</a></li> 41<li><a href="#mfcport">How do I port MFC applications to wxWidgets?</a></li> 42<li><a href="#crash">Why do I sometimes get bizarre crash problems using VC++ 5/6?</a></li> 43<li><a href="#makefiles">How are the wxWidgets makefiles edited under Windows?</a></li> 44<li><a href="#vcdebug">How do you use VC++'s memory leak checking instead of that in wxWidgets?</a></li> 45<li><a href="#shortcutproblem">Why are menu hotkeys or shortcuts not working in my application?</a></li> 46<li><a href="#regconfig">Why can I not write to the HKLM part of the registry with wxRegConfig?</a></li> 47<li><a href="#access">Is MS Active Accessibility supported?</a></li> 48<li><a href="#dspfmt">Why does Visual C++ complain about corrupted project files?</a></li> 49<li><a href="#crtmismatch">Visual C++ gives errors about multiply defined symbols, what can I do?</a></li> 50<li><a href="#directx">Why do I get compilation errors when using wxWidgets with DirectShow?</a></li> 51<li><a href="#handlewm">How do I handle Windows messages in my wxWidgets program?</a></li> 52</ul> 53<hr> 54 55<h3><a name="platforms">Which Windows platforms are supported?</a></h3> 56 57wxWidgets can be used to develop and deliver applications on Windows 95, Windows 98, Windows NT, 58Windows 2000, Windows XP, and Windows Vista. A Windows CE 59port is also available (see below).<P> 60 6116-bit compilation is only supported for wxWidgets 2.4 and previous versions, 62using Visual C++ 1.5 and Borland BC++ 4 to 5. 63<P> 64 65wxWidgets for Windows will also compile on Unix with gcc using Wine from <a href="http://www.winehq.org" target=_top>WineHQ</a>. 66The resulting executables are Unix binaries that work with the Wine Windows API emulator.<P> 67 68You can also compile wxWidgets for Windows on Unix with Cygwin or Mingw32, resulting 69in executables that will run on Windows. So in theory you could write your applications 70using wxGTK or wxMotif, then check/debug your wxWidgets for Windows 71programs with Wine, and finally produce an ix86 Windows executable using Cygwin/Mingw32, 72without ever needing a copy of Microsoft Windows. See the Technical Note on the Web site detailing cross-compilation.<P> 73 74<h3><a name="wince">What about Windows CE?</a></h3> 75 76This port supports Pocket PC 2002/2003 and MS Smartphone 2002/2003, using 77Embedded Visual C++ 3 or 4. For further information, see the wxMSW section in 78the wxWidgets Reference Manual, and also the <a href="http://www.wxwidgets.org/embedded.htm#wxwince">wxEmbedded</a> page.<P> 79 80<h3><a name="winxp">What do I need to do for Windows XP?</a></h3> 81 82From wxWidgets 2.5, the XP manifest is included in wx/msw/wx.rc and 83so your application will be themed automatically so long as you include wx.rc 84in your own .rc file.<P> 85 86For versions of wxWidgets below 2.5, you need to provide the manifest 87explicitly, as follows.<p> 88 89In the same directory as you have your executable (e.g. foo.exe) you 90put a file called foo.exe.manifest in which you have something like 91the following: 92 93<pre> 94<?xml version="1.0" encoding="UTF-8" standalone="yes"?> 95<assembly 96 xmlns="urn:schemas-microsoft-com:asm.v1" 97 manifestVersion="1.0"> 98<assemblyIdentity 99 processorArchitecture="x86" 100 version="5.1.0.0" 101 type="win32" 102 name="foo.exe"/> 103 <description>Foo program</description> 104 <dependency> 105 <dependentAssembly> 106 <assemblyIdentity 107 type="win32" 108 name="Microsoft.Windows.Common-Controls" 109 version="6.0.0.0" 110 publicKeyToken="6595b64144ccf1df" 111 language="*" 112 processorArchitecture="x86"/> 113 </dependentAssembly> 114 </dependency> 115</assembly> 116</pre> 117 118If you want to add it to your application permanently, 119you can also include it in your .rc file using this 120line:<P> 121 122<PRE> 123 1 24 "winxp.manifest" 124</PRE> 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 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?</a></h3> 150 151It's partly a matter of taste, but some people prefer Visual C++ since the debugger is very 152good, it's very stable, the documentation is extensive, and it generates small executables. 153Since project files are plain text, it's easy for me to generate appropriate project files 154for wxWidgets samples.<P> 155 156Borland C++ is fine - and very fast - but it's hard (impossible?) to use the debugger without using project files, and 157the debugger is nowhere near up to VC++'s quality. The IDE isn't great.<P> 158 159C++Builder's power isn't really used with wxWidgets since it needs integration with its 160own class library (VCL). For wxWidgets, I've only used it with makefiles, in which case 161it's almost identical to BC++ 5.0 (the same makefiles can be used).<P> 162 163You can't beat Cygwin's price (free), and you can debug adequately using gdb. However, it'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'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. However BC++ has trouble compiling large executables statically, 174so you need to dynamically link the wxWidgets libraries.<p> 175 176<h3><a name="unicode">Is Unicode supported?</a></h3> 177 178Yes, Unicode is fully supported under Windows NT/2000 and there is limited 179support for it under Windows 9x using <a 180href="http://www.microsoft.com/globaldev/handson/dev/mslu_announce.mspx">MSLU</a>. 181<p> 182 183<h3><a name="doublebyte">Does wxWidgets support double byte fonts (Chinese/Japanese/Korean etc.)?</a></h3> 184 185For Japanese under Win2000, it seems that wxWidgets has no problems working 186with double byte char sets (meaning DBCS, not Unicode). First you have to 187install Japanese support on your Win2K system and choose for ANSI translation 188<tt>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CodePage=932</tt> 189(default is 1252 for Western). Then you can see all the Japanese letters in 190wxWidgets applications. 191<p> 192 193<h3><a name="dll">Can you compile wxWidgets as a DLL?</a></h3> 194 195Yes (using the Visual C++ or Borland C++ makefile), but be aware that distributing DLLs is a thorny issue 196and you may be better off compiling statically-linked applications, unless you're 197delivering a suite of separate programs, or you're compiling a lot of wxWidgets applications 198and have limited hard disk space.<P> 199 200With a DLL approach, and with different versions and configurations of wxWidgets 201needing to be catered for, the end user may end up with a host of large DLLs in his or her Windows system directory, 202negating the point of using DLLs. Of course, this is not a problem just associated with 203wxWidgets! 204<P> 205 206<h3><a name="exesize">How can I reduce executable size?</a></h3> 207 208You can compile wxWidgets as a DLL (see above, VC++/BC++ only at present). You should also 209compile your programs for release using non-debugging and space-optimisation options, but 210take with VC++ 5/6 space optimisation: it can sometimes cause problems.<P> 211 212If you want to distribute really small executables, you can 213use <a href="http://www.un4seen.com/petite/" target=_top>Petite</a> 214by Ian Luck. This nifty utility compresses Windows executables by around 50%, so your 500KB executable 215will shrink to a mere 250KB. With this sort of size, there is reduced incentive to 216use DLLs. Another good compression tool (probably better than Petite) is <a href="http://upx.sourceforge.net/" target=_top>UPX</a>. 217<P> 218 219Please do not be surprised if MinGW produces a statically-linked minimal executable of 1 MB. Firstly, gcc 220produces larger executables than some compilers. Secondly, this figure will 221include most of the overhead of wxWidgets, so as your application becomes more 222complex, the overhead becomes proportionally less significant. And thirdly, trading executable compactness 223for the enormous increase in productivity you get with wxWidgets is almost always well worth it.<P> 224 225If you have a really large executable compiled with MinGW (for example 20MB) then 226you need to configure wxWidgets to compile without debugging information: see 227docs/msw/install.txt for details. You may find that using configure instead 228of makefile.g95 is easier, particularly since you can maintain debug and 229release versions of the library simultaneously, in different directories. 230Also, run 'strip' after linking to remove all traces of debug info. 231<P> 232 233<H3><a name="mfc">Is wxWidgets compatible with MFC?</a></H3> 234 235There is a sample which demonstrates MFC and wxWidgets code co-existing in the same 236application. However, don't expect to be able to enable wxWidgets windows with OLE-2 237functionality using MFC.<P> 238 239<H3><a name="setuph">Why do I get errors about setup.h not being found?</a></H3> 240 241When you build the wxWidgets library, setup.h is copied 242from include/wx/msw/setup.h to e.g. lib/vc_msw/mswd/wx/setup.h (the path 243depends on the configuration you're building). So you need to add 244this include path if building using the static Debug library:<P> 245 246lib/vc_lib/mswd<P> 247 248or if building the static Release library, lib/vc_lib/msw.<P> 249 250See also the <a href="http://wiki.wxwidgets.org/wiki.pl?Table_Of_Contents">wxWiki Contents</a> 251for more information.<P> 252 253 254<H3><a name="asuffix">Why do I get errors about FooBarA when I only use FooBar in my program?</H3> 255 256If you get errors like 257<p> 258<center> 259<tt>no matching function for call to 'wxDC::DrawTextA(const char[5], int, 260int)'</tt> 261</center> 262<p> 263or similar ones for the other functions, i.e. the compiler error messages 264mention the function with the <tt>'A'</tt> suffix while you didn't 265use it in your code, the explanation is that you had included 266<tt><windows.h></tt> header which redefines many symbols to have such 267suffix (or <tt>'W'</tt> in the Unicode builds). 268 269<p> 270The fix is to either not include <tt><windows.h></tt> at all or include 271<tt>"wx/msw/winundef.h"</tt> immediately after it. 272 273<H3><a name="newerrors">Why my code fails to compile with strange errors about new operator?</a></H3> 274 275The most common cause of this problem is the memory debugging settings in 276<tt>wx/msw/setup.h</tt>. You have several choices: 277 278<ul> 279 <li> Either disable overloading the global operator new completely by 280 setting <tt>wxUSE_GLOBAL_MEMORY_OPERATORS</tt> and 281 <tt>wxUSE_DEBUG_NEW_ALWAYS</tt> to 0 in this file 282 <li> Or leave them on but do <tt>#undef new</tt> after including any 283 wxWidgets headers, like this the memory debugging will be still on 284 for wxWidgets sources but off for your own code 285</ul> 286 287Notice that IMHO the first solution is preferable for VC++ users who can use 288the <a href="#vcdebug">VC++ CRT memory debugging features</a> instead. 289 290<H3><a name="mfcport">How do I port MFC applications to wxWidgets?</a></H3> 291 292Set up your interface from scratch using wxWidgets (especially <a href="http://www.robeling.de" target=_top>wxDesigner</a> 293or <a href="http://www.anthemion.co.uk/dialogblocks/" target=_new>DialogBlocks</a> -- 294it'll save you a <i>lot</i> of time) and when you have a shell prepared, you can start 295'pouring in' code from the MFC app, with appropriate 296modifications. This is the approach I have used, and I found 297it very satisfactory. A two-step process then - reproduce the bare 298interface first, then wire it up afterwards. That way you deal 299with each area of complexity separately. Don't try to think MFC 300and wxWidgets simultaneously from the beginning - it is easier to 301reproduce the initial UI by looking at the behaviour of the MFC 302app, not its code. 303 304<H3><a name="crash">Why do I sometimes get bizarre crash problems using VC++ 5/6?</a></H3> 305 306Some crash problems can be due to inconsistent compiler 307options (and of course this isn't limited to wxWidgets). 308If strange/weird/impossible things start to happen please 309check (dumping IDE project file as makefile and doing text comparison 310if necessary) that the project settings, especially the list of defined 311symbols, struct packing, etc. are exactly the same for all items in 312the project. After this, delete everything (including PCH) and recompile.<P> 313 314VC++ 5's optimization code seems to be broken and can 315cause problems: this can be seen when deleting an object Dialog 316Editor, in Release mode with optimizations on. If in doubt, 317switch off optimisations, although this will result in much 318larger executables. It seems possible that the library can be created with 319strong optimization, so long as the application is not strongly 320optimized. For example, in wxWidgets project, set to 'Minimum 321Size'. In Dialog Editor project, set to 'Customize: Favor Small 322Code' (and no others). This will then work.<P> 323 324<H3><a name="makefiles">How are the wxWidgets makefiles edited under Windows?</a></H3> 325 326wxWidgets 2.5.x and above uses Bakefile to generate makefiles, which 327is described in technical note 16 under docs/tech in your distribution.<p> 328 329For 2.4.x, there is a system written by Vadim Zeitlin that 330generates the makefiles from templates using tmake.<P> 331 332Here are Vadim's notes on tmake:<P> 333 334<blockquote> 335To use these new makefiles, you don'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'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's a Perl5 program and so it needs Perl (doh). There is a binary for 345Windows (available from the same page), but I haven't used it, so 346I don't know if it works as flawlessly as "perl tmake" does (note 347for people knowing Perl: don't try to run tmake with -w, it won'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't have any of Borland, Watcom or 354Symantec and I don'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'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'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't create vc5.t because 381I don't need it and can'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'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'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++'s memory leak checking instead of that in wxWidgets?</a></H3> 404 405Vadim Zeitlin: 406 407<pre> 408On the VC++ level, it'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'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'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'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 errors 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> This causes compilation errors within DirectShow: 551> 552> wxutil.h(125) : error C2065: 'EXECUTE_ASSERT' : undeclared identifier 553> amfilter.h(1099) : error C2065: 'ASSERT' : undeclared identifier 554 555The reason for this is that __WXDEBUG__ is also used by the DXSDK (9.0 556in my case) to '#pragma once' the contents of 557DXSDK/Samples/C++/DirectShow/BaseClasses/wxdebug.h. So if __WXDEBUG__ 558is defined, then wxdebug.h doesn't get included, and the assert macros 559don't get defined. You have to #undef __WXDEBUG__ before including the 560directshow baseclass's <streams.h>. 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. 570 571 572</font> 573 574</BODY> 575 576</HTML> 577