Some work on GTK focus handling and events.

[wxWidgets.git] / docs / latex / wx / app.tex

diff --git a/docs/latex/wx/app.tex b/docs/latex/wx/app.tex
index a9044b7132fd86a7e15fe8792fd85e411475dc88..b830069460c24716842917986353ef5a797fab96 100644 (file)
--- a/docs/latex/wx/app.tex
+++ b/docs/latex/wx/app.tex
@@ -38,9 +38,6 @@ a reference to your application object) to be visible to other files.
 
 Constructor. Called implicitly with a definition of a wxApp object.
 
 
 Constructor. Called implicitly with a definition of a wxApp object.
 

-The argument is a language identifier; this is an experimental
-feature and will be expanded and documented in future versions.
-

 \membersection{wxApp::\destruct{wxApp}}
 
 \func{void}{\destruct{wxApp}}{\void}
 \membersection{wxApp::\destruct{wxApp}}
 
 \func{void}{\destruct{wxApp}}{\void}


@@ -120,32 +117,48 @@ manner to refer to the application.
 
 \helpref{wxApp::SetClassName}{wxappsetclassname}
 
 
 \helpref{wxApp::SetClassName}{wxappsetclassname}
 

-\membersection{wxApp::GetExitOnDelete}\label{wxappgetexitondelete}
+\membersection{wxApp::GetExitOnFrameDelete}\label{wxappgetexitonframedelete}

 
 

-\constfunc{bool}{GetExitOnDelete}{\void}
+\constfunc{bool}{GetExitFrameOnDelete}{\void}

 
 Returns TRUE if the application will exit when the top-level window is deleted, FALSE
 otherwise.
 
 \wxheading{See also}
 
 
 Returns TRUE if the application will exit when the top-level window is deleted, FALSE
 otherwise.
 
 \wxheading{See also}
 

-\helpref{wxApp::SetExitOnDelete}{wxappsetexitondelete}
+\helpref{wxApp::SetExitOnFrameDelete}{wxappsetexitonframedelete}

 
 

-\membersection{wxApp::GetPrintMode}\label{wxappgetprintmode}
+\membersection{wxApp::GetTopWindow}\label{wxappgettopwindow}

 
 

-\constfunc{bool}{GetPrintMode}{\void}
+\constfunc{virtual wxWindow *}{GetTopWindow}{\void}

 
 

-Returns the print mode: see \helpref{wxApp::SetPrintMode}{wxappsetprintmode}.
+Returns a pointer to the top window.

 
 

-\membersection{wxApp::GetTopWindow}\label{wxappgettopwindow}
+\wxheading{Remarks}

 
 

-\constfunc{wxWindow *}{GetTopWindow}{\void}
+If the top window hasn't been set using \helpref{wxApp::SetTopWindow}{wxappsettopwindow}, this
+function will find the first top-level window (frame or dialog) and return that.

 
 

-Returns a pointer to the top window.
+\wxheading{See also}
+
+\helpref{SetTopWindow}{wxappsettopwindow}
+
+\membersection{wxApp::GetUseBestVisual}\label{wxappgetusebestvisual}
+
+\constfunc{bool}{GetUseBestVisual}{\void}
+
+Returns TRUE if the application will use the best visual on systems that support
+different visuals, FALSE otherwise.

 
 \wxheading{See also}
 
 
 \wxheading{See also}
 

-\helpref{wxApp::SetTopWindow}{wxappsettopwindow}
+\helpref{SetUseBestVisual}{wxappsetusebestvisual}
+
+\membersection{wxApp::GetVendorName}\label{wxappgetvendorname}
+
+\constfunc{wxString}{GetVendorName}{\void}
+
+Returns the application's vendor name.

 
 \membersection{wxApp::ExitMainLoop}\label{wxappexitmainloop}
 
 
 \membersection{wxApp::ExitMainLoop}\label{wxappexitmainloop}
 


@@ -176,16 +189,64 @@ to provide your own (environment-dependent) main loop.
 
 Returns 0 under X, and the wParam of the WM\_QUIT message under Windows.
 
 
 Returns 0 under X, and the wParam of the WM\_QUIT message under Windows.
 

-\membersection{wxApp::OnActivate}\label{wxapponactivate}
+%% VZ: OnXXX() functions should *not* be documented
+%%
+%%\membersection{wxApp::OnActivate}\label{wxapponactivate}
+%%
+%%\func{void}{OnActivate}{\param{wxActivateEvent\& }{event}}
+%%
+%%Provide this member function to know whether the application is being
+%%activated or deactivated (Windows only).
+%%
+%%\wxheading{See also}
+%%
+%%\helpref{wxWindow::OnActivate}{wxwindowonactivate}, \helpref{wxActivateEvent}{wxactivateevent}
+%%
+%%\membersection{wxApp::OnCharHook}\label{wxapponcharhook}
+%%
+%%\func{void}{OnCharHook}{\param{wxKeyEvent\&}{ event}}
+%%
+%%This event handler function is called (under Windows only) to allow the window to intercept keyboard events
+%%before they are processed by child windows.
+%%
+%%\wxheading{Parameters}
+%%
+%%\docparam{event}{The keypress event.}
+%%
+%%\wxheading{Remarks}
+%%
+%%Use the wxEVT\_CHAR\_HOOK macro in your event table.
+%%
+%%If you use this member, you can selectively consume keypress events by calling\rtfsp
+%%\helpref{wxEvent::Skip}{wxeventskip} for characters the application is not interested in.
+%%
+%%\wxheading{See also}
+%%
+%%\helpref{wxKeyEvent}{wxkeyevent}, \helpref{wxWindow::OnChar}{wxwindowonchar},\rtfsp
+%%\helpref{wxWindow::OnCharHook}{wxwindowoncharhook}, \helpref{wxDialog::OnCharHook}{wxdialogoncharhook}
+
+\membersection{wxApp::OnAssert}\label{wxapponassert}
+
+\func{void}{OnAssert}{\param{const wxChar }{*file}, \param{int }{line}, \param{const wxChar }{*msg}}
+
+This function is called when an assert failure occurs, i.e. the condition
+specified in \helpref{wxASSERT}{wxassert} macro evaluated to {\tt FALSE}.
+It is only called in debug mode (when {\tt \_\_WXDEBUG\_\_} is defined) as
+asserts are not left in the release code at all.
+
+The base class version show the default assert failure dialog box proposing to
+the user to stop the program, continue or ignore all subsequent asserts.

 
 

-\func{void}{OnActivate}{\param{wxActivateEvent\& }{event}}
+\wxheading{Parameters}

 
 

-Provide this member function to know whether the application is being
-activated or deactivated (Windows only).
+\docparam{file}{the name of the source file where the assert occured}

 
 

-\wxheading{See also}
+\docparam{line}{the line number in this file where the assert occured}

 
 

-\helpref{wxWindow::OnActivate}{wxwindowonactivate}, \helpref{wxActivateEvent}{wxactivateevent}
+\docparam{msg}{the message specified as argument to 
+\helpref{wxASSERT\_MSG}{wxassertmsg} or \helpref{wxFAIL\_MSG}{wxfailmsg}, will
+be {\tt NULL} if just \helpref{wxASSERT}{wxassert} or \helpref{wxFAIL}{wxfail} 
+was used}

 
 \membersection{wxApp::OnExit}\label{wxapponexit}
 
 
 \membersection{wxApp::OnExit}\label{wxapponexit}
 


@@ -194,87 +255,143 @@ activated or deactivated (Windows only).
 Provide this member function for any processing which needs to be done as
 the application is about to exit.
 
 Provide this member function for any processing which needs to be done as
 the application is about to exit.
 

-\membersection{wxApp::OnCharHook}\label{wxapponcharhook}
+\membersection{wxApp::OnCmdLineError}\label{wxapponcmdlineerror}

 
 

-\func{void}{OnCharHook}{\param{wxKeyEvent\&}{ event}}
+\func{bool}{OnCmdLineError}{\param{wxCmdLineParser\& }{parser}}

 
 

-This event handler function is called (under Windows only) to allow the window to intercept keyboard events
-before they are processed by child windows.
+Called when command line parsing fails (i.e. an incorrect command line option
+was specified by the user). The default behaviour is to show the program usage
+text and abort the program.

 
 

-\wxheading{Parameters}
-
-\docparam{event}{The keypress event.}
+Return {\tt TRUE} to continue normal execution or {\tt FALSE} to return 
+{\tt FALSE} from \helpref{OnInit}{wxapponinit} thus terminating the program.

 
 

-\wxheading{Remarks}
+\wxheading{See also}

 
 

-Use the wxEVT\_CHAR\_HOOK macro in your event table.
+\helpref{OnInitCmdLine}{wxapponinitcmdline}

 
 

-If you use this member, you can selectively consume keypress events by calling\rtfsp
-\helpref{wxEvent::Skip}{wxeventskip} for characters the application is not interested in.
+\membersection{wxApp::OnCmdLineHelp}\label{wxapponcmdlinehelp}

 
 

-\wxheading{See also}
+\func{bool}{OnCmdLineHelp}{\param{wxCmdLineParser\& }{parser}}

 
 

-\helpref{wxKeyEvent}{wxkeyevent}, \helpref{wxWindow::OnChar}{wxwindowonchar},\rtfsp
-\helpref{wxWindow::OnCharHook}{wxwindowoncharhook}, \helpref{wxDialog::OnCharHook}{wxdialogoncharhook}
+Called when the help option ({\tt --help}) was specified on the command line.
+The default behaviour is to show the program usage text and abort the program.

 
 

-\membersection{wxApp::OnIdle}\label{wxapponidle}
+Return {\tt TRUE} to continue normal execution or {\tt FALSE} to return 
+{\tt FALSE} from \helpref{OnInit}{wxapponinit} thus terminating the program.

 
 

-\func{void}{OnIdle}{\param{wxIdleEvent\& }{event}}
+\wxheading{See also}

 
 

-Override this member function for any processing which needs to be done
-when the application is idle. You should call wxApp::OnIdle from your own function,
-since this forwards OnIdle events to windows and also performs garbage collection for
-windows whose destruction has been delayed.
+\helpref{OnInitCmdLine}{wxapponinitcmdline}

 
 

-wxWindows' strategy for OnIdle processing is as follows. After pending user interface events for an
-application have all been processed, wxWindows sends an OnIdle event to the application object. wxApp::OnIdle itself
-sends an OnIdle event to each application window, allowing windows to do idle processing such as updating
-their appearance. If either wxApp::OnIdle or a window OnIdle function requested more time, by
-caling \helpref{wxIdleEvent::ReqestMore}{wxidleeventrequestmore}, wxWindows will send another OnIdle
-event to the application object. This will occur in a loop until either a user event is found to be
-pending, or OnIdle requests no more time. Then all pending user events are processed until the system
-goes idle again, when OnIdle is called, and so on.
+\membersection{wxApp::OnCmdLineParsed}\label{wxapponcmdlineparsed}

 
 

-\wxheading{See also}
+\func{bool}{OnCmdLineParsed}{\param{wxCmdLineParser\& }{parser}}

 
 

-\helpref{wxWindow::OnIdle}{wxwindowonidle}, \helpref{wxIdleEvent}{wxidleevent},\rtfsp
-\helpref{wxWindow::SendIdleEvents}{wxappsendidleevents}
+Called after the command line had been successfully parsed. You may override
+this method to test for the values of the various parameters which could be
+set from the command line.

 
 

-\membersection{wxApp::OnEndSession}\label{wxapponendsession}
+Don't forget to call the base class version unless you want to suppress
+processing of the standard command line options.

 
 

-\func{void}{OnEndSession}{\param{wxCloseEvent\& }{event}}
+Return {\tt TRUE} to continue normal execution or {\tt FALSE} to return 
+{\tt FALSE} from \helpref{OnInit}{wxapponinit} thus terminating the program.

 
 

-This is an event handler function called when the operating system or GUI session is
-about to close down. The application has a chance to silently save information,
-and can optionally close itself.
+\wxheading{See also}

 
 

-Use the EVT\_END\_SESSION event table macro to handle query end session events.
+\helpref{OnInitCmdLine}{wxapponinitcmdline}

 
 

-The default handler calls \helpref{wxWindow::Close}{wxwindowclose} with a TRUE argument
-(forcing the application to close itself silently).
+\membersection{wxApp::OnFatalException}\label{wxapponfatalexception}

 
 

-\wxheading{Remarks}
+\func{void}{OnFatalException}{\void}

 
 

-Under X, OnEndSession is called in response to the 'die' event.
+This function may be called if something fatal happens: an unhandled
+exception under Win32 or a a fatal signal under Unix, for example. However,
+this will not happen by default: you have to explicitly call 
+\helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions} to enable this.

 
 

-Under Windows, OnEndSession is called in response to the WM\_ENDSESSION message.
+Generally speaking, this function should only show a message to the user and
+return. You may attempt to save unsaved data but this is not guaranteed to
+work and, in fact, probably won't.

 
 \wxheading{See also}
 
 
 \wxheading{See also}
 

-\helpref{wxWindow::Close}{wxwindowclose},\rtfsp
-\helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp
-\helpref{wxCloseEvent}{wxcloseevent},\rtfsp
-\helpref{wxApp::OnQueryEndSession}{wxapponqueryendsession}
+\helpref{wxHandleFatalExcetions}{wxhandlefatalexceptions}
+
+%% VZ: the wxApp event handler are private and should not be documented here!
+%%
+%%\membersection{wxApp::OnIdle}\label{wxapponidle}
+%%
+%%\func{void}{OnIdle}{\param{wxIdleEvent\& }{event}}
+%%
+%%Override this member function for any processing which needs to be done
+%%when the application is idle. You should call wxApp::OnIdle from your own function,
+%%since this forwards OnIdle events to windows and also performs garbage collection for
+%%windows whose destruction has been delayed.
+%%
+%%wxWindows' strategy for OnIdle processing is as follows. After pending user interface events for an
+%%application have all been processed, wxWindows sends an OnIdle event to the application object. wxApp::OnIdle itself
+%%sends an OnIdle event to each application window, allowing windows to do idle processing such as updating
+%%their appearance. If either wxApp::OnIdle or a window OnIdle function requested more time, by
+%%caling \helpref{wxIdleEvent::RequestMore}{wxidleeventrequestmore}, wxWindows will send another OnIdle
+%%event to the application object. This will occur in a loop until either a user event is found to be
+%%pending, or OnIdle requests no more time. Then all pending user events are processed until the system
+%%goes idle again, when OnIdle is called, and so on.
+%%
+%%\wxheading{See also}
+%%
+%%\helpref{wxWindow::OnIdle}{wxwindowonidle}, \helpref{wxIdleEvent}{wxidleevent},\rtfsp
+%%\helpref{wxWindow::SendIdleEvents}{wxappsendidleevents}
+%%
+%%\membersection{wxApp::OnEndSession}\label{wxapponendsession}
+%%
+%%\func{void}{OnEndSession}{\param{wxCloseEvent\& }{event}}
+%%
+%%This is an event handler function called when the operating system or GUI session is
+%%about to close down. The application has a chance to silently save information,
+%%and can optionally close itself.
+%%
+%%Use the EVT\_END\_SESSION event table macro to handle query end session events.
+%%
+%%The default handler calls \helpref{wxWindow::Close}{wxwindowclose} with a TRUE argument
+%%(forcing the application to close itself silently).
+%%
+%%\wxheading{Remarks}
+%%
+%%Under X, OnEndSession is called in response to the `die' event.
+%%
+%%Under Windows, OnEndSession is called in response to the WM\_ENDSESSION message.
+%%
+%%\wxheading{See also}
+%%
+%%\helpref{wxWindow::Close}{wxwindowclose},\rtfsp
+%%\helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp
+%%\helpref{wxCloseEvent}{wxcloseevent},\rtfsp
+%%\helpref{wxApp::OnQueryEndSession}{wxapponqueryendsession}

 
 \membersection{wxApp::OnInit}\label{wxapponinit}
 
 \func{bool}{OnInit}{\void}
 
 This must be provided by the application, and will usually create the
 
 \membersection{wxApp::OnInit}\label{wxapponinit}
 
 \func{bool}{OnInit}{\void}
 
 This must be provided by the application, and will usually create the

-application's main window, calling \helpref{wxApp::SetTopWindow}{wxappsettopwindow}.
+application's main window, optionally calling 
+\helpref{wxApp::SetTopWindow}{wxappsettopwindow}.
+
+Notice that if you want to to use the command line processing provided by
+wxWindows you have to call the base class version in the derived class
+OnInit().

 
 Return TRUE to continue processing, FALSE to exit the application.
 
 
 Return TRUE to continue processing, FALSE to exit the application.
 

+\membersection{wxApp::OnInitCmdLine}\label{wxapponinitcmdline}
+
+\func{void}{OnInitCmdLine}{\param{wxCmdLineParser\& }{parser}}
+
+Called from \helpref{OnInit}{wxapponinit} and may be used to initialize the
+parser with the command line options for this application. The base class
+versions adds support for a few standard options only.
+

 \membersection{wxApp::OnQueryEndSession}\label{wxapponqueryendsession}
 
 \func{void}{OnQueryEndSession}{\param{wxCloseEvent\& }{event}}
 \membersection{wxApp::OnQueryEndSession}\label{wxapponqueryendsession}
 
 \func{void}{OnQueryEndSession}{\param{wxCloseEvent\& }{event}}


@@ -300,7 +417,7 @@ and vetoes the shutdown if Close returns FALSE. This will be sufficient for many
 
 \wxheading{Remarks}
 
 
 \wxheading{Remarks}
 

-Under X, OnQueryEndSession is called in response to the 'save session' event.
+Under X, OnQueryEndSession is called in response to the `save session' event.

 
 Under Windows, OnQueryEndSession is called in response to the WM\_QUERYENDSESSION message.
 
 
 Under Windows, OnQueryEndSession is called in response to the WM\_QUERYENDSESSION message.
 


@@ -308,8 +425,9 @@ Under Windows, OnQueryEndSession is called in response to the WM\_QUERYENDSESSIO
 
 \helpref{wxWindow::Close}{wxwindowclose},\rtfsp
 \helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp
 
 \helpref{wxWindow::Close}{wxwindowclose},\rtfsp
 \helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp

-\helpref{wxCloseEvent}{wxcloseevent},\rtfsp
-\helpref{wxApp::OnEndSession}{wxapponendsession}
+\helpref{wxCloseEvent}{wxcloseevent}
+%% GD: OnXXX functions are not documented
+%%\helpref{wxApp::OnEndSession}{wxapponendsession}

 
 \membersection{wxApp::ProcessMessage}\label{wxappprocessmessage}
 
 
 \membersection{wxApp::ProcessMessage}\label{wxappprocessmessage}
 


@@ -339,8 +457,7 @@ BOOL CTheApp::PreTranslateMessage(MSG *msg)
 
 \func{bool}{Pending}{\void}
 
 
 \func{bool}{Pending}{\void}
 

-Returns TRUE if unprocessed events are in the window system event queue
-(MS Windows and Motif).
+Returns TRUE if unprocessed events are in the window system event queue.

 
 \wxheading{See also}
 
 
 \wxheading{See also}
 


@@ -363,7 +480,10 @@ If TRUE is returned, more OnIdle processing is requested by one or more window.
 
 \wxheading{See also}
 
 
 \wxheading{See also}
 

-\helpref{wxApp::OnIdle}{wxapponidle}, \helpref{wxWindow::OnIdle}{wxwindowonidle}, \helpref{wxIdleEvent}{wxidleevent}
+%% GD: OnXXX functions are not documented
+%%\helpref{wxApp::OnIdle}{wxapponidle}
+\helpref{wxWindow::OnIdle}{wxwindowonidle},\rtfsp
+\helpref{wxIdleEvent}{wxidleevent}

 
 \membersection{wxApp::SetAppName}\label{wxappsetappname}
 
 
 \membersection{wxApp::SetAppName}\label{wxappsetappname}
 


@@ -407,9 +527,9 @@ manner to refer to the application.
 
 \helpref{wxApp::GetClassName}{wxappgetclassname}
 
 
 \helpref{wxApp::GetClassName}{wxappgetclassname}
 

-\membersection{wxApp::SetExitOnDelete}\label{wxappsetexitondelete}
+\membersection{wxApp::SetExitOnFrameDelete}\label{wxappsetexitonframedelete}

 
 

-\func{void}{SetExitOnDelete}{\param{bool}{ flag}}
+\func{void}{SetExitOnFrameDelete}{\param{bool}{ flag}}

 
 Allows the programmer to specify whether the application will exit when the
 top-level frame is deleted.
 
 Allows the programmer to specify whether the application will exit when the
 top-level frame is deleted.


@@ -419,41 +539,93 @@ top-level frame is deleted.
 \docparam{flag}{If TRUE (the default), the application will exit when the top-level frame is
 deleted. If FALSE, the application will continue to run.}
 
 \docparam{flag}{If TRUE (the default), the application will exit when the top-level frame is
 deleted. If FALSE, the application will continue to run.}
 

-\wxheading{Remarks}
+\membersection{wxApp::SetTopWindow}\label{wxappsettopwindow}
+
+\func{void}{SetTopWindow}{\param{wxWindow* }{window}}
+
+Sets the `top' window. You can call this from within \helpref{wxApp::OnInit}{wxapponinit} to
+let wxWindows know which is the main window. You don't have to set the top window;
+it is only a convenience so that (for example) certain dialogs without parents can use a
+specific window as the top window. If no top window is specified by the application,
+wxWindows just uses the first frame or dialog in its top-level window list, when it
+needs to use the top window.
+
+\wxheading{Parameters}
+
+\docparam{window}{The new top window.}
+
+\wxheading{See also}
+
+\helpref{wxApp::GetTopWindow}{wxappgettopwindow}, \helpref{wxApp::OnInit}{wxapponinit}
+

 
 

-Currently, setting this to FALSE only has an effect under Windows.
+\membersection{wxApp::SetVendorName}\label{wxappsetvendorname}

 
 

-\membersection{wxApp::SetPrintMode}\label{wxappsetprintmode}
+\func{void}{SetVendorName}{\param{const wxString\& }{name}}

 
 

-\func{void}{SetPrintMode}{\param{int}{ mode}}
+Sets the name of application's vendor. The name will be used
+in registry access. A default name is set by
+wxWindows.

 
 

-Sets the print mode determining what printing facilities will be
-used by the printing framework.
+\wxheading{See also}
+
+\helpref{wxApp::GetVendorName}{wxappgetvendorname}
+
+\membersection{wxApp::GetStdIcon}\label{wxappgetstdicon}
+
+\func{virtual wxIcon}{GetStdIcon}{\param{int }{which}} const
+
+Returns the icons used by wxWindows internally, e.g. the ones used for 
+message boxes.  This function is used internally and 
+can be overridden by the user to change the default icons.

 
 \wxheading{Parameters}
 
 
 \wxheading{Parameters}
 

-\docparam{mode}{This can be one of:
+\docparam{which}{One of the wxICON\_XXX specifies which icon to return.}

 
 

-\begin{twocollist}\itemsep=0pt
-\twocolitem{{\bf wxPRINT\_WINDOWS}}{Under Windows, use Windows printing (wxPrinterDC). This is the
-default under Windows.}
-\twocolitem{{\bf wxPRINT\_POSTSCRIPT}}{Use PostScript printing (wxPostScriptDC). This is the
-default for non-Windows platforms.}
-\end{twocollist}
-}%
+See \helpref{wxMessageBox}{wxmessagebox} for a list of icon identifiers.

 
 

-\membersection{wxApp::SetTopWindow}\label{wxappsettopwindow}
+\membersection{wxApp::SetUseBestVisual}\label{wxappsetusebestvisual}

 
 

-\func{void}{SetTopWindow}{\param{wxWindow* }{window}}
+\func{void}{SetUseBestVisual}{\param{bool}{ flag}}
+
+Allows the programmer to specify whether the application will use the best visual
+on systems that support several visual on the same display. This is typically the
+case under Solaris and IRIX, where the default visual is only 8-bit whereas certain
+appications are supposed to run in TrueColour mode.
+
+Note that this function has to be called in the constructor of the {\tt wxApp} 
+instance and won't have any effect when called later on.

 
 

-Sets the `top' window. You should normally call this from within \helpref{wxApp::OnInit}{wxapponinit} to
-let wxWindows know which is the main window.
+This function currently only has effect under GTK.

 
 \wxheading{Parameters}
 
 
 \wxheading{Parameters}
 

-\docparam{window}{The new top window.}
+\docparam{flag}{If TRUE, the app will use the best visual.}

 
 

-\wxheading{See also}
+\membersection{wxApp::Yield}\label{wxappyield}

 
 

-\helpref{wxApp::GetTopWindow}{wxappgettopwindow}, \helpref{wxApp::OnInit}{wxapponinit}
+\func{bool}{Yield}{\param{bool}{ onlyIfNeeded = FALSE}}
+
+Yields control to pending messages in the windowing system. This can be useful, for example, when a
+time-consuming process writes to a text window. Without an occasional
+yield, the text window will not be updated properly, and on systems with
+cooperative multitasking, such as Windows 3.1 other processes will not respond.
+
+Caution should be exercised, however, since yielding may allow the
+user to perform actions which are not compatible with the current task.
+Disabling menu items or whole menus during processing can avoid unwanted
+reentrance of code: see \helpref{::wxSafeYield}{wxsafeyield} for a better
+function.
+
+Note that Yield() will not flush the message logs. This is intentional as
+calling Yield() is usually done to quickly update the screen and popping up a
+message box dialog may be undesirable. If you do wish to flush the log
+messages immediately (otherwise it will be done during the next idle loop
+iteration), call \helpref{wxLog::FlushActive}{wxlogflushactive}.
+
+Calling Yield() recursively is normally an error and an assert failure is
+raised in debug build if such situation is detected. However if the the 
+{\it onlyIfNeeded} parameter is {\tt TRUE}, the method will just silently
+return {\tt FALSE} instead.