Tk_CreateEventHandler(3)				       Tk Library Procedures					  Tk_CreateEventHandler(3)

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NAME

       Tk_CreateEventHandler, Tk_DeleteEventHandler - associate procedure callback with an X event

SYNOPSIS

       #include <tk.h>

       Tk_CreateEventHandler(tkwin, mask, proc, clientData)

       Tk_DeleteEventHandler(tkwin, mask, proc, clientData)

ARGUMENTS

       Tk_Window tkwin (in)		      Token for window in which events may occur.

       unsigned long mask (in)		      Bit-mask of events (such as ButtonPressMask) for which proc should be called.

       Tk_EventProc *proc (in)		      Procedure to invoke whenever an event in mask occurs in the window given by tkwin.

       ClientData clientData (in)	      Arbitrary one-word value to pass to proc.
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DESCRIPTION

       Tk_CreateEventHandler  arranges for proc to be invoked in the future whenever one of the event types specified by mask occurs in the window
       specified by tkwin.  The callback to proc will be made by Tk_HandleEvent; this mechanism  only  works  in  programs  that  dispatch  events
       through Tk_HandleEvent (or through other Tk procedures that call Tk_HandleEvent, such as Tk_DoOneEvent or Tk_MainLoop).

       Proc should have arguments and result that match the type Tk_EventProc:
	      typedef void Tk_EventProc(
		  ClientData clientData,
		  XEvent *eventPtr);
       The  clientData parameter to proc is a copy of the clientData argument given to Tk_CreateEventHandler when the callback was created.  Typi-
       cally, clientData points to a data structure containing application-specific information about the window  in  which  the  event  occurred.
       EventPtr is a pointer to the X event, which will be one of the ones specified in the mask argument to Tk_CreateEventHandler.

       Tk_DeleteEventHandler may be called to delete a previously-created event handler:  it deletes the first handler it finds that is associated
       with tkwin and matches the mask, proc, and clientData arguments.  If no such handler exists, then Tk_HandleEvent returns without doing any-
       thing.	Although  Tk  supports	it, it's probably a bad idea to have more than one callback with the same mask, proc, and clientData argu-
       ments.  When a window is deleted all of its handlers will be deleted automatically;  in this case there is no need to  call  Tk_DeleteEven-
       tHandler.

       If multiple handlers are declared for the same type of X event on the same window, then the handlers will be invoked in the order they were
       created.

KEYWORDS

       bind, callback, event, handler

Tk															  Tk_CreateEventHandler(3)