XmGetVisibility man page
XmGetVisibility — A function that determines if a widget is visible
#include <Xm/Xm.h> XmVisibility XmGetVisibility( Widget widget);
XmGetVisibility returns the visibility state of the specified widget. It checks to see if some part of the widget's rectangular area is unobscured by the widget's ancestors, or some part of the widget's rectangular area is inside the work window (but possibly outside the clip window) of a ScrolledWindow whose XmNscrollingPolicy is XmAUTOMATIC and whose XmNtraverseObscuredCallback is not NULL.
XmGetVisibility does not check to see if widget is obscured by its siblings or by siblings of its ancestors. Consequently, XmGetVisibility returns XmVISIBILITY_UNOBSCURED for widgets which are completely or partially covered by one or more siblings of widget by one or more siblings of ancestors of widget.
When a widget which is unrealized is being queried, it is indicated that the widget is fully obscured. If an application unmaps a widget that has its XmNmappedWhenManaged resource set to True, the return value is undefined. When a widget which is unmanaged is being queried, it is indicated that the widget is fully obscured.
Specifies the ID of the widget
Returns one of the following values:
Indicates that the widget is mapped, not obscured, and is completely visible on the screen.
Indicates that the widget is mapped, and is not completely visible on the screen (partially obscured).
Indicates that the widget is not at all visible on the screen.
XmIsTraversable(3), XmManager(3), and XmProcessTraversal(3).