https://invisible-island.net/xterm/xtoolkit/
XtQueryGeometry - query the preferred geometry of a child widget
#include <X11/Intrinsic.h>
XtGeometryResult XtQueryGeometry(Widget w, XtWidgetGeometry *intended,
XtWidgetGeometry *preferred_return);
intended Specifies any changes the parent plans to make to the child's
geometry or NULL.
preferred_return
Returns the child widget's preferred geometry.
w Specifies the widget.
To discover a child's preferred geometry, the child's parent sets any
changes that it intends to make to the child's geometry in the corre-
sponding fields of the intended structure, sets the corresponding bits
in intended.request_mode, and calls XtQueryGeometry.
XtQueryGeometry clears all bits in the preferred_return->request_mode
and checks the query_geometry field of the specified widget's class
record. If query_geometry is not NULL, XtQueryGeometry calls the
query_geometry procedure and passes as arguments the specified widget,
intended, and preferred_return structures. If the intended argument is
NULL, XtQueryGeometry replaces it with a pointer to an XtWidgetGeometry
structure with request_mode=0 before calling query_geometry.
XtConfigureWidget(3), XtMakeGeometryRequest(3)
X Toolkit Intrinsics – C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.1.5.2 XtQueryGeometry(3)