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1 \section{\class{wxApp}}\label{wxapp}
2
3 The {\bf wxApp} class represents the application itself. It is used
4 to:
5
6 \begin{itemize}\itemsep=0pt
7 \item set and get application-wide properties;
8 \item implement the windowing system message or event loop;
9 \item initiate application processing via \helpref{wxApp::OnInit}{wxapponinit};
10 \item allow default processing of events not handled by other
11 objects in the application.
12 \end{itemize}
13
14 You should use the macro IMPLEMENT\_APP(appClass) in your application implementation
15 file to tell wxWidgets how to create an instance of your application class.
16
17 Use DECLARE\_APP(appClass) in a header file if you want the wxGetApp function (which returns
18 a reference to your application object) to be visible to other files.
19
20 \wxheading{Derived from}
21
22 \helpref{wxEvtHandler}{wxevthandler}\\
23 \helpref{wxObject}{wxobject}
24
25 \wxheading{Include files}
26
27 <wx/app.h>
28
29 \wxheading{See also}
30
31 \helpref{wxApp overview}{wxappoverview}
32
33 \latexignore{\rtfignore{\wxheading{Members}}}
34
35
36 \membersection{wxApp::wxApp}\label{wxappctor}
37
38 \func{}{wxApp}{\void}
39
40 Constructor. Called implicitly with a definition of a wxApp object.
41
42
43 \membersection{wxApp::\destruct{wxApp}}\label{wxappdtor}
44
45 \func{virtual}{\destruct{wxApp}}{\void}
46
47 Destructor. Will be called implicitly on program exit if the wxApp
48 object is created on the stack.
49
50
51 \membersection{wxApp::argc}\label{wxappargc}
52
53 \member{int}{argc}
54
55 Number of command line arguments (after environment-specific processing).
56
57
58 \membersection{wxApp::argv}\label{wxappargv}
59
60 \member{wxChar **}{argv}
61
62 Command line arguments (after environment-specific processing).
63
64
65 \membersection{wxApp::CreateLogTarget}\label{wxappcreatelogtarget}
66
67 \func{virtual wxLog*}{CreateLogTarget}{\void}
68
69 Creates a wxLog class for the application to use for logging errors. The default
70 implementation returns a new wxLogGui class.
71
72 \wxheading{See also}
73
74 \helpref{wxLog}{wxlog}
75
76
77 \membersection{wxApp::Dispatch}\label{wxappdispatch}
78
79 \func{virtual void}{Dispatch}{\void}
80
81 Dispatches the next event in the windowing system event queue.
82
83 This can be used for programming event loops, e.g.
84
85 \begin{verbatim}
86 while (app.Pending())
87 Dispatch();
88 \end{verbatim}
89
90 \wxheading{See also}
91
92 \helpref{wxApp::Pending}{wxapppending}
93
94
95 \membersection{wxApp::ExitMainLoop}\label{wxappexitmainloop}
96
97 \func{virtual void}{ExitMainLoop}{\void}
98
99 Call this to explicitly exit the main message (event) loop.
100 You should normally exit the main loop (and the application) by deleting
101 the top window.
102
103
104 \membersection{wxApp::FilterEvent}\label{wxappfilterevent}
105
106 \func{int}{FilterEvent}{\param{wxEvent\& }{event}}
107
108 This function is called before processing any event and allows the application
109 to preempt the processing of some events. If this method returns $-1$ the event
110 is processed normally, otherwise either {\tt true} or {\tt false} should be
111 returned and the event processing stops immediately considering that the event
112 had been already processed (for the former return value) or that it is not
113 going to be processed at all (for the latter one).
114
115
116 \membersection{wxApp::GetAppName}\label{wxappgetappname}
117
118 \constfunc{wxString}{GetAppName}{\void}
119
120 Returns the application name.
121
122 \wxheading{Remarks}
123
124 wxWidgets sets this to a reasonable default before
125 calling \helpref{wxApp::OnInit}{wxapponinit}, but the application can reset it at will.
126
127
128 \membersection{wxApp::GetClassName}\label{wxappgetclassname}
129
130 \constfunc{wxString}{GetClassName}{\void}
131
132 Gets the class name of the application. The class name may be used in a platform specific
133 manner to refer to the application.
134
135 \wxheading{See also}
136
137 \helpref{wxApp::SetClassName}{wxappsetclassname}
138
139
140 \membersection{wxApp::GetExitOnFrameDelete}\label{wxappgetexitonframedelete}
141
142 \constfunc{bool}{GetExitOnFrameDelete}{\void}
143
144 Returns true if the application will exit when the top-level window is deleted, false
145 otherwise.
146
147 \wxheading{See also}
148
149 \helpref{wxApp::SetExitOnFrameDelete}{wxappsetexitonframedelete},\\
150 \helpref{wxApp shutdown overview}{wxappshutdownoverview}
151
152
153 \membersection{wxApp::GetInstance}\label{wxappgetinstance}
154
155 \func{static wxAppConsole *}{GetInstance}{\void}
156
157 Returns the one and only global application object.
158 Usually \texttt{wxTheApp} is usead instead.
159
160 \wxheading{See also}
161
162 \helpref{wxApp::SetInstance}{wxappsetinstance}
163
164
165 \membersection{wxApp::GetTopWindow}\label{wxappgettopwindow}
166
167 \constfunc{virtual wxWindow *}{GetTopWindow}{\void}
168
169 Returns a pointer to the top window.
170
171 \wxheading{Remarks}
172
173 If the top window hasn't been set using \helpref{wxApp::SetTopWindow}{wxappsettopwindow}, this
174 function will find the first top-level window (frame or dialog) and return that.
175
176 \wxheading{See also}
177
178 \helpref{SetTopWindow}{wxappsettopwindow}
179
180
181 \membersection{wxApp::GetUseBestVisual}\label{wxappgetusebestvisual}
182
183 \constfunc{bool}{GetUseBestVisual}{\void}
184
185 Returns true if the application will use the best visual on systems that support
186 different visuals, false otherwise.
187
188 \wxheading{See also}
189
190 \helpref{SetUseBestVisual}{wxappsetusebestvisual}
191
192
193 \membersection{wxApp::GetVendorName}\label{wxappgetvendorname}
194
195 \constfunc{wxString}{GetVendorName}{\void}
196
197 Returns the application's vendor name.
198
199
200 \membersection{wxApp::IsActive}\label{wxappisactive}
201
202 \constfunc{bool}{IsActive}{\void}
203
204 Returns \true if the application is active, i.e. if one of its windows is
205 currently in the foreground. If this function returns \false and you need to
206 attract users attention to the application, you may use
207 \helpref{wxTopLevelWindow::RequestUserAttention}{wxtoplevelwindowrequestuserattention}
208 to do it.
209
210
211 \membersection{wxApp::IsMainLoopRunning}\label{wxappismainlooprunning}
212
213 \func{static bool}{IsMainLoopRunning}{\void}
214
215 Returns \true if the main event loop is currently running, i.e. if the
216 application is inside \helpref{OnRun}{wxapponrun}.
217
218 This can be useful to test whether the events can be dispatched. For example,
219 if this function returns \false, non-blocking sockets cannot be used because
220 the events from them would never be processed.
221
222
223 \membersection{wxApp::MainLoop}\label{wxappmainloop}
224
225 \func{virtual int}{MainLoop}{\void}
226
227 Called by wxWidgets on creation of the application. Override this if you wish
228 to provide your own (environment-dependent) main loop.
229
230 \wxheading{Return value}
231
232 Returns 0 under X, and the wParam of the WM\_QUIT message under Windows.
233
234 %% VZ: OnXXX() functions should *not* be documented
235 %%
236 %%\membersection{wxApp::OnActivate}\label{wxapponactivate}
237 %%
238 %%\func{void}{OnActivate}{\param{wxActivateEvent\& }{event}}
239 %%
240 %%Provide this member function to know whether the application is being
241 %%activated or deactivated (Windows only).
242 %%
243 %%\wxheading{See also}
244 %%
245 %%\helpref{wxWindow::OnActivate}{wxwindowonactivate}, \helpref{wxActivateEvent}{wxactivateevent}
246 %%
247 %%\membersection{wxApp::OnCharHook}\label{wxapponcharhook}
248 %%
249 %%\func{void}{OnCharHook}{\param{wxKeyEvent\&}{ event}}
250 %%
251 %%This event handler function is called (under Windows only) to allow the window to intercept keyboard events
252 %%before they are processed by child windows.
253 %%
254 %%\wxheading{Parameters}
255 %%
256 %%\docparam{event}{The keypress event.}
257 %%
258 %%\wxheading{Remarks}
259 %%
260 %%Use the wxEVT\_CHAR\_HOOK macro in your event table.
261 %%
262 %%If you use this member, you can selectively consume keypress events by calling\rtfsp
263 %%\helpref{wxEvent::Skip}{wxeventskip} for characters the application is not interested in.
264 %%
265 %%\wxheading{See also}
266 %%
267 %%\helpref{wxKeyEvent}{wxkeyevent}, \helpref{wxWindow::OnChar}{wxwindowonchar},\rtfsp
268 %%\helpref{wxWindow::OnCharHook}{wxwindowoncharhook}, \helpref{wxDialog::OnCharHook}{wxdialogoncharhook}
269
270
271 \membersection{wxApp::OnAssertFailure}\label{wxapponassertfailure}
272
273 \func{void}{OnAssertFailure}{\param{const wxChar }{*file}, \param{int }{line}, \param{const wxChar }{*func}, \param{const wxChar }{*cond}, \param{const wxChar }{*msg}}
274
275 This function is called when an assert failure occurs, i.e. the condition
276 specified in \helpref{wxASSERT}{wxassert} macro evaluated to {\tt false}.
277 It is only called in debug mode (when {\tt \_\_WXDEBUG\_\_} is defined) as
278 asserts are not left in the release code at all.
279
280 The base class version shows the default assert failure dialog box proposing to
281 the user to stop the program, continue or ignore all subsequent asserts.
282
283 \wxheading{Parameters}
284
285 \docparam{file}{the name of the source file where the assert occurred}
286
287 \docparam{line}{the line number in this file where the assert occurred}
288
289 \docparam{func}{the name of the function where the assert occurred, may be
290 empty if the compiler doesn't support C99 \texttt{\_\_FUNCTION\_\_}}
291
292 \docparam{cond}{the condition of the failed assert in text form}
293
294 \docparam{msg}{the message specified as argument to
295 \helpref{wxASSERT\_MSG}{wxassertmsg} or \helpref{wxFAIL\_MSG}{wxfailmsg}, will
296 be {\tt NULL} if just \helpref{wxASSERT}{wxassert} or \helpref{wxFAIL}{wxfail}
297 was used}
298
299
300 \membersection{wxApp::OnCmdLineError}\label{wxapponcmdlineerror}
301
302 \func{bool}{OnCmdLineError}{\param{wxCmdLineParser\& }{parser}}
303
304 Called when command line parsing fails (i.e. an incorrect command line option
305 was specified by the user). The default behaviour is to show the program usage
306 text and abort the program.
307
308 Return {\tt true} to continue normal execution or {\tt false} to return
309 {\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program.
310
311 \wxheading{See also}
312
313 \helpref{OnInitCmdLine}{wxapponinitcmdline}
314
315
316 \membersection{wxApp::OnCmdLineHelp}\label{wxapponcmdlinehelp}
317
318 \func{bool}{OnCmdLineHelp}{\param{wxCmdLineParser\& }{parser}}
319
320 Called when the help option ({\tt --help}) was specified on the command line.
321 The default behaviour is to show the program usage text and abort the program.
322
323 Return {\tt true} to continue normal execution or {\tt false} to return
324 {\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program.
325
326 \wxheading{See also}
327
328 \helpref{OnInitCmdLine}{wxapponinitcmdline}
329
330
331 \membersection{wxApp::OnCmdLineParsed}\label{wxapponcmdlineparsed}
332
333 \func{bool}{OnCmdLineParsed}{\param{wxCmdLineParser\& }{parser}}
334
335 Called after the command line had been successfully parsed. You may override
336 this method to test for the values of the various parameters which could be
337 set from the command line.
338
339 Don't forget to call the base class version unless you want to suppress
340 processing of the standard command line options.
341
342 Return {\tt true} to continue normal execution or {\tt false} to return
343 {\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program.
344
345 \wxheading{See also}
346
347 \helpref{OnInitCmdLine}{wxapponinitcmdline}
348
349
350 \membersection{wxApp::OnExceptionInMainLoop}\label{wxapponexceptioninmainloop}
351
352 \func{virtual bool}{OnExceptionInMainLoop}{\void}
353
354 This function is called if an unhandled exception occurs inside the main
355 application event loop. It can return \true to ignore the exception and to
356 continue running the loop or \false to exit the loop and terminate the
357 program. In the latter case it can also use C++ \texttt{throw} keyword to
358 rethrow the current exception.
359
360 The default behaviour of this function is the latter in all ports except under
361 Windows where a dialog is shown to the user which allows him to choose between
362 the different options. You may override this function in your class to do
363 something more appropriate.
364
365 Finally note that if the exception is rethrown from here, it can be caught in
366 \helpref{OnUnhandledException}{wxapponunhandledexception}.
367
368
369 \membersection{wxApp::OnExit}\label{wxapponexit}
370
371 \func{virtual int}{OnExit}{\void}
372
373 Override this member function for any processing which needs to be
374 done as the application is about to exit. OnExit is called after
375 destroying all application windows and controls, but before
376 wxWidgets cleanup. Note that it is not called at all if
377 \helpref{OnInit}{wxapponinit} failed.
378
379 The return value of this function is currently ignored, return the same value
380 as returned by the base class method if you override it.
381
382
383 \membersection{wxApp::OnFatalException}\label{wxapponfatalexception}
384
385 \func{void}{OnFatalException}{\void}
386
387 This function may be called if something fatal happens: an unhandled
388 exception under Win32 or a a fatal signal under Unix, for example. However,
389 this will not happen by default: you have to explicitly call
390 \helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions} to enable this.
391
392 Generally speaking, this function should only show a message to the user and
393 return. You may attempt to save unsaved data but this is not guaranteed to
394 work and, in fact, probably won't.
395
396 \wxheading{See also}
397
398 \helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions}
399
400 %% VZ: the wxApp event handler are private and should not be documented here!
401 %%
402 %%\membersection{wxApp::OnIdle}\label{wxapponidle}
403 %%
404 %%\func{void}{OnIdle}{\param{wxIdleEvent\& }{event}}
405 %%
406 %%Override this member function for any processing which needs to be done
407 %%when the application is idle. You should call wxApp::OnIdle from your own function,
408 %%since this forwards OnIdle events to windows and also performs garbage collection for
409 %%windows whose destruction has been delayed.
410 %%
411 %%wxWidgets' strategy for OnIdle processing is as follows. After pending user interface events for an
412 %%application have all been processed, wxWidgets sends an OnIdle event to the application object. wxApp::OnIdle itself
413 %%sends an OnIdle event to each application window, allowing windows to do idle processing such as updating
414 %%their appearance. If either wxApp::OnIdle or a window OnIdle function requested more time, by
415 %%calling \helpref{wxIdleEvent::RequestMore}{wxidleeventrequestmore}, wxWidgets will send another OnIdle
416 %%event to the application object. This will occur in a loop until either a user event is found to be
417 %%pending, or OnIdle requests no more time. Then all pending user events are processed until the system
418 %%goes idle again, when OnIdle is called, and so on.
419 %%
420 %%\wxheading{See also}
421 %%
422 %%\helpref{wxWindow::OnIdle}{wxwindowonidle}, \helpref{wxIdleEvent}{wxidleevent},\rtfsp
423 %%\helpref{wxWindow::SendIdleEvents}{wxappsendidleevents}
424 %%
425 %%\membersection{wxApp::OnEndSession}\label{wxapponendsession}
426 %%
427 %%\func{void}{OnEndSession}{\param{wxCloseEvent\& }{event}}
428 %%
429 %%This is an event handler function called when the operating system or GUI session is
430 %%about to close down. The application has a chance to silently save information,
431 %%and can optionally close itself.
432 %%
433 %%Use the EVT\_END\_SESSION event table macro to handle query end session events.
434 %%
435 %%The default handler calls \helpref{wxWindow::Close}{wxwindowclose} with a true argument
436 %%(forcing the application to close itself silently).
437 %%
438 %%\wxheading{Remarks}
439 %%
440 %%Under X, OnEndSession is called in response to the `die' event.
441 %%
442 %%Under Windows, OnEndSession is called in response to the WM\_ENDSESSION message.
443 %%
444 %%\wxheading{See also}
445 %%
446 %%\helpref{wxWindow::Close}{wxwindowclose},\rtfsp
447 %%\helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp
448 %%\helpref{wxCloseEvent}{wxcloseevent},\rtfsp
449
450
451 \membersection{wxApp::OnInit}\label{wxapponinit}
452
453 \func{bool}{OnInit}{\void}
454
455 This must be provided by the application, and will usually create the
456 application's main window, optionally calling
457 \helpref{wxApp::SetTopWindow}{wxappsettopwindow}. You may use
458 \helpref{OnExit}{wxapponexit} to clean up anything initialized here, provided
459 that the function returns \true.
460
461 Notice that if you want to to use the command line processing provided by
462 wxWidgets you have to call the base class version in the derived class
463 OnInit().
464
465 Return \true to continue processing, \false to exit the application
466 immediately.
467
468
469 \membersection{wxApp::OnInitCmdLine}\label{wxapponinitcmdline}
470
471 \func{void}{OnInitCmdLine}{\param{wxCmdLineParser\& }{parser}}
472
473 Called from \helpref{OnInit}{wxapponinit} and may be used to initialize the
474 parser with the command line options for this application. The base class
475 versions adds support for a few standard options only.
476
477 \membersection{wxApp::OnRun}\label{wxapponrun}
478
479 \func{virtual int}{OnRun}{\void}
480
481 This virtual function is where the execution of a program written in wxWidgets
482 starts. The default implementation just enters the main loop and starts
483 handling the events until it terminates, either because
484 \helpref{ExitMainLoop}{wxappexitmainloop} has been explicitly called or because
485 the last frame has been deleted and
486 \helpref{GetExitOnFrameDelete}{wxappgetexitonframedelete} flag is \true (this
487 is the default).
488
489 The return value of this function becomes the exit code of the program, so it
490 should return $0$ in case of successful termination.
491
492
493 \membersection{wxApp::OnUnhandledException}\label{wxapponunhandledexception}
494
495 \func{virtual void}{OnUnhandledException}{\void}
496
497 This function is called when an unhandled C++ exception occurs inside
498 \helpref{OnRun()}{wxapponrun} (the exceptions which occur during the program
499 startup and shutdown might not be caught at all).
500 Note that the exception type is lost by now, so if you want to really handle
501 the exception you should override \helpref{OnRun()}{wxapponrun} and put a
502 try/catch clause around the call to the base class version there.
503
504
505 \membersection{wxApp::ProcessMessage}\label{wxappprocessmessage}
506
507 \func{bool}{ProcessMessage}{\param{WXMSG *}{msg}}
508
509 Windows-only function for processing a message. This function
510 is called from the main message loop, checking for windows that
511 may wish to process it. The function returns true if the message
512 was processed, false otherwise. If you use wxWidgets with another class
513 library with its own message loop, you should make sure that this
514 function is called to allow wxWidgets to receive messages. For example,
515 to allow co-existence with the Microsoft Foundation Classes, override
516 the PreTranslateMessage function:
517
518 \begin{verbatim}
519 // Provide wxWidgets message loop compatibility
520 BOOL CTheApp::PreTranslateMessage(MSG *msg)
521 {
522 if (wxTheApp && wxTheApp->ProcessMessage((WXMSW *)msg))
523 return true;
524 else
525 return CWinApp::PreTranslateMessage(msg);
526 }
527 \end{verbatim}
528
529
530 \membersection{wxApp::Pending}\label{wxapppending}
531
532 \func{virtual bool}{Pending}{\void}
533
534 Returns true if unprocessed events are in the window system event queue.
535
536 \wxheading{See also}
537
538 \helpref{wxApp::Dispatch}{wxappdispatch}
539
540
541 \membersection{wxApp::SendIdleEvents}\label{wxappsendidleevents}
542
543 \func{bool}{SendIdleEvents}{\param{wxWindow*}{ win}, \param{wxIdleEvent\& }{event}}
544
545 Sends idle events to a window and its children.
546
547 Please note that this function is internal to wxWidgets and shouldn't be used
548 by user code.
549
550 \wxheading{Remarks}
551
552 These functions poll the top-level windows, and their children, for idle event processing.
553 If true is returned, more OnIdle processing is requested by one or more window.
554
555 \wxheading{See also}
556
557 \helpref{wxIdleEvent}{wxidleevent}
558
559
560 \membersection{wxApp::SetAppName}\label{wxappsetappname}
561
562 \func{void}{SetAppName}{\param{const wxString\& }{name}}
563
564 Sets the name of the application. The name may be used in dialogs
565 (for example by the document/view framework). A default name is set by
566 wxWidgets.
567
568 \wxheading{See also}
569
570 \helpref{wxApp::GetAppName}{wxappgetappname}
571
572
573 \membersection{wxApp::SetClassName}\label{wxappsetclassname}
574
575 \func{void}{SetClassName}{\param{const wxString\& }{name}}
576
577 Sets the class name of the application. This may be used in a platform specific
578 manner to refer to the application.
579
580 \wxheading{See also}
581
582 \helpref{wxApp::GetClassName}{wxappgetclassname}
583
584
585 \membersection{wxApp::SetExitOnFrameDelete}\label{wxappsetexitonframedelete}
586
587 \func{void}{SetExitOnFrameDelete}{\param{bool}{ flag}}
588
589 Allows the programmer to specify whether the application will exit when the
590 top-level frame is deleted.
591
592 \wxheading{Parameters}
593
594 \docparam{flag}{If true (the default), the application will exit when the top-level frame is
595 deleted. If false, the application will continue to run.}
596
597 \wxheading{See also}
598
599 \helpref{wxApp::GetExitOnFrameDelete}{wxappgetexitonframedelete},\\
600 \helpref{wxApp shutdown overview}{wxappshutdownoverview}
601
602
603 \membersection{wxApp::SetInstance}\label{wxappsetinstance}
604
605 \func{static void}{SetInstance}{\param{wxAppConsole* }{app}}
606
607 Allows external code to modify global \texttt{wxTheApp}, but you should really
608 know what you're doing if you call it.
609
610 \wxheading{Parameters}
611
612 \docparam{app}{Replacement for the global application object.}
613
614 \wxheading{See also}
615
616 \helpref{wxApp::GetInstance}{wxappgetinstance}
617
618
619 \membersection{wxApp::SetTopWindow}\label{wxappsettopwindow}
620
621 \func{void}{SetTopWindow}{\param{wxWindow* }{window}}
622
623 Sets the `top' window. You can call this from within \helpref{wxApp::OnInit}{wxapponinit} to
624 let wxWidgets know which is the main window. You don't have to set the top window;
625 it is only a convenience so that (for example) certain dialogs without parents can use a
626 specific window as the top window. If no top window is specified by the application,
627 wxWidgets just uses the first frame or dialog in its top-level window list, when it
628 needs to use the top window.
629
630 \wxheading{Parameters}
631
632 \docparam{window}{The new top window.}
633
634 \wxheading{See also}
635
636 \helpref{wxApp::GetTopWindow}{wxappgettopwindow}, \helpref{wxApp::OnInit}{wxapponinit}
637
638
639
640 \membersection{wxApp::SetVendorName}\label{wxappsetvendorname}
641
642 \func{void}{SetVendorName}{\param{const wxString\& }{name}}
643
644 Sets the name of application's vendor. The name will be used
645 in registry access. A default name is set by
646 wxWidgets.
647
648 \wxheading{See also}
649
650 \helpref{wxApp::GetVendorName}{wxappgetvendorname}
651
652
653 \membersection{wxApp::SetUseBestVisual}\label{wxappsetusebestvisual}
654
655 \func{void}{SetUseBestVisual}{\param{bool}{ flag}}
656
657 Allows the programmer to specify whether the application will use the best visual
658 on systems that support several visual on the same display. This is typically the
659 case under Solaris and IRIX, where the default visual is only 8-bit whereas certain
660 applications are supposed to run in TrueColour mode.
661
662 Note that this function has to be called in the constructor of the {\tt wxApp}
663 instance and won't have any effect when called later on.
664
665 This function currently only has effect under GTK.
666
667 \wxheading{Parameters}
668
669 \docparam{flag}{If true, the app will use the best visual.}
670
671
672 \membersection{wxApp::HandleEvent}\label{wxapphandleevent}
673
674 \constfunc{virtual void}{HandleEvent}{\param{wxEvtHandler}{ *handler}, \param{wxEventFunction}{ func}, \param{wxEvent\& }{event}}
675
676 This function simply invokes the given method \arg{func} of the specified
677 event handler \arg{handler} with the \arg{event} as parameter. It exists solely
678 to allow to catch the C++ exceptions which could be thrown by all event
679 handlers in the application in one place: if you want to do this, override this
680 function in your wxApp-derived class and add try/catch clause(s) to it.
681
682
683 \membersection{wxApp::Yield}\label{wxappyield}
684
685 \func{bool}{Yield}{\param{bool}{ onlyIfNeeded = false}}
686
687 Yields control to pending messages in the windowing system. This can be useful, for example, when a
688 time-consuming process writes to a text window. Without an occasional
689 yield, the text window will not be updated properly, and on systems with
690 cooperative multitasking, such as Windows 3.1 other processes will not respond.
691
692 Caution should be exercised, however, since yielding may allow the
693 user to perform actions which are not compatible with the current task.
694 Disabling menu items or whole menus during processing can avoid unwanted
695 reentrance of code: see \helpref{::wxSafeYield}{wxsafeyield} for a better
696 function.
697
698 Note that Yield() will not flush the message logs. This is intentional as
699 calling Yield() is usually done to quickly update the screen and popping up a
700 message box dialog may be undesirable. If you do wish to flush the log
701 messages immediately (otherwise it will be done during the next idle loop
702 iteration), call \helpref{wxLog::FlushActive}{wxlogflushactive}.
703
704 Calling Yield() recursively is normally an error and an assert failure is
705 raised in debug build if such situation is detected. However if the
706 {\it onlyIfNeeded} parameter is {\tt true}, the method will just silently
707 return {\tt false} instead.
708