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