XmeAddFocusChangeCallback(XmeAddFocusChangeCallback(library call)
NAME
XmeAddFocusChangeCallback - Registers a callback for focus
changes
SYNOPSIS
#include <Xm/VendorSEP.h>
void XmeAddFocusChangeCallback(
Widget widget,
XtCallbackProc callbackprocedure,
XtPointer data);
DESCRIPTION
XmeAddFocusChangeCallback registers a callback_procedure to
be called whenever there is a focus change to any widget in
the widget tree managed by a specified VendorShell or
subclass of VendorShell. This callback_procedure is called
the focus change callback. Motif will not call the focus
change callbacks when the VendorShell (or subclass) is in
implicit mode. In explicit mode, Motif automatically calls
the focus change callbacks whenever the user or the
application attempts to change focus. Your focus change
callback procedure has the option of accepting or rejecting
the attempted focus change.
Registering a focus change callback can cause an entire
application to run more slowly because the focus change
callbacks might be called fairly frequently.
A focus change callback can be removed by calling
XmeRemoveFocusChangeCallback.
widget Specifies the widget whose children are to be
monitored for focus changes. The specified widget
must be a VendorShell or a subclass of
VendorShell.
callback_procedure
Specifies the callback procedure to be called
whenever there is a focus change.
data Specifies the call data to be passed as the
call_data argument to the callback procedure.
Motif passes a pointer to an XmFocusMovedCallbackStruct to
callback_procedure. When callback_procedure returns, Motif
examines the cont field only.
typedef struct {
int reason ;
XEvent *event;
Boolean cont;
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XmeAddFocusChangeCallback(XmeAddFocusChangeCallback(library call)
Widget old_focus;
Widget new_focus;
unsigned char focus_policy;
XmTraversalDirection direction;
} XmFocusMovedCallbackStruct;
reason Indicates why the callback was invoked. Motif
always sets this field to XmCRFOCUSMOVED.
event Points to the event that triggered the callback.
cont Indicates whether an attempted focus change will
be allowed or rejected. A focus change callback
should set contto True (the default) to permit the
focus change. A focus change callback should set
cont to False to reject the focus change.
Therefore, if you set cont to False, Motif will
ensure that the focus stays at widget old_focus.
old_focus Indicates the widget ID of the widget that had
keyboard focus immediately prior to the most
recent traversal.
new_focus Indicates the widget ID of the widget that has
just gotten keyboard focus.
focus_policy
Indicates the VendorShell's keyboard focus policy;
this will always be XmEXPLICIT since
callback_procedure only gets called in explicit
mode.
direction Specifies the direction of the traversal. (See
XmProcessTraversal(3) in the Motif Programmer's
Referencefor details on possible values of the
XmTraversalDirection enumerated type.)
RELATED
XmeRemoveFocusChangeCallback(3).
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