XmQTtakesDefault(3X) UNIX System V XmQTtakesDefault(3X)
NAME
XmQTtakesDefault - A button widget holding this trait can
change its appearance to show that it is the default button
SYNOPSIS
#include <Xm/TakesDefT.h>
typedef struct {
int version;
XmTakesDefaultNotifyProc showAsDefault;
} XmTakesDefaultTraitRec, *XmTakesDefaultTrait;
void (*XmTakesDefaultNotifyProc)(
Widget,
XtEnum);
VERSION
This page documents Motif 2.1.
DESCRIPTION
You will use the XmQTtakesDefault trait if you are writing a
PushButton-style primitive widget or a DialogBox-style
manager widget.
A DialogBox widget displays several PushButton-style
children. For example, a typical DialogBox widget might
display three PushButton widgets: an OK button, a Cancel
button, and a Help button. One of these PushButton-style
children should be the default button. The default button
is the PushButton-style child that is activated when the
user presses <Return> anywhere in the widget. (The
parent_process method of the DialogBox is responsible for
detecting the activation event.)
A PushButton-style widget must be capable of altering its
appearance to show that it is the default choice. Most
PushButton-style widgets do this by highlighting their
borders in a special way.
If you are writing a PushButton-style widget, then your
widget should hold the XmQTtakesDefault trait. This trait
announces to DialogBox widgets that the child is capable of
changing its appearance to show that it is the default
choice. Conversely, if you are writing a DialogBox widget,
then your DialogBox widget should examine its button
children for this trait.
The following standard Motif primitives hold this trait:
o XmPushButton
o XmPushButtonGadget
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XmQTtakesDefault(3X) UNIX System V XmQTtakesDefault(3X)
In addition, the ExmCommandButton demonstrates how to
install this trait and how to define a showAsDefault trait
method.
The following standard Motif managers examine their children
widgets for this trait and call the showAsDefault trait
method:
o XmBulletinBoard and all its subclasses
The showAsDefault Trait Method
void showAsDefault(
Widget childWidget,
XtEnum state);
Every PushButton-style widget holding the XmQTtakesDefault
trait must provide a showAsDefault trait method. The
DialogBox that manages the PushButton-style widgets will
call the XmQTtakesDefault trait method, each time passing a
different value of state. The typical sequence of calls from
the DialogBox manager is as follows:
o The DialogBox calls the showAsDefault trait method of
each child widget, specifying a state of
XmDEFAULT_READY. This message tells the child to
prepare to become the default button. The Motif Style
Guidedoes not mandate a particular way of handling
this message, so your widget may visually do as you
please. One possible response would be to increase the
widget's internal margins. (Calling XmDEFAULT_READY
helps the manager avoid future unnecessary geometry
requests.)
o The DialogBox calls the showAsDefault trait method of
the chosen default child, specifying a state of
XmDEFAULT_ON. This message tells the child to become
the default button. The child must change its visual
appearance in some way to show the user that it is now
the default button. For example, the ExmCommandButton
demonstration widget increases its shadow thickness to
show that it is the default. Another widget might
display some sort of icon (perhaps an arrow) to
symbolize that it is the default button.
o If the default child widget changes, then the
DialogBox calls the showAsDefault trait method twice.
The first call specifies a state of XmDEFAULT_OFF in
order to turn off one default button. The second call
specifies a state of XmDEFAULT_ON in order to turn on
the new default button. Upon receiving the
XmDEFAULT_OFF message, the child widget must change
its appearance to show that it is no longer the
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default.
XmDEFAULT_FORGET resets the visual appearance of a child
widget so that it looks as it did prior to the
XmDEFAULT_READYcall.
childWidget
Specifies the child widget holding this trait.
state Specifies one of the following states:
XmDEFAULT_READY, XmDEFAULT_ON, XmDEFAULT_OFF, and
XmDEFAULT_FORGET.
RELATED
XmBulletinBoard(3), XmPushButton(3), and
ExmCommandButton(3).
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