https://invisible-island.net/xterm/xtoolkit/
XtCreateApplicationContext, XtDestroyApplicationContext, XtWidgetTo-
ApplicationContext, XtToolkitInitialize - create, destroy, and obtain
an application context
#include <X11/Intrinsic.h>
XtAppContext XtCreateApplicationContext(void);
void XtDestroyApplicationContext(XtAppContext app_context);
XtAppContext XtWidgetToApplicationContext(Widget w);
void XtToolkitInitialize(void);
app_context
Specifies the application context.
w Specifies the widget that you want the application context
for.
The XtCreateApplicationContext function returns an application context,
which is an opaque type. Every application must have at least one
application context.
The XtDestroyApplicationContext function destroys the specified appli-
cation context as soon as it is safe to do so. If called from with an
event dispatch (for example, a callback procedure), XtDestroy-
ApplicationContext does not destroy the application context until the
dispatch is complete.
The XtWidgetToApplicationContext function returns the application con-
text for the specified widget.
The XtToolkitInitialize function initializes the Intrinsics internals.
If XtToolkitInitialize was previously called it returns immediately.
XtDisplayInitialize(3)
X Toolkit Intrinsics – C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.1.5.2 XtCreateApplicationContext(3)