man : XmIsTraversable(3)
XmIsTraversable -- A function that identifies whether a widget can be
XmIsTraversable determines whether the specified widget is eligible to
receive focus through keyboard traversal. In general, a widget is eli-
gible to receive focus when all of the following conditions are true:
o The widget and its ancestors are not being destroyed, are sensi-
tive, and have a value of True for XmNtraversalOn.
o The widget and its ancestors are realized, managed, and (except
for gadgets) mapped. If an application unmaps a widget that has
its XmNmappedWhenManaged resource set to True, the return value
o 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.
Some widgets may not be eligible to receive focus even if they meet all
these conditions. For example, most managers cannot receive focus
through keyboard traversal. Some widgets may be eligible to receive
focus under particular conditions. For example, a DrawingArea is eli-
gible to receive focus if it meets the conditions above and has no
child whose XmNtraversalOn resource is True.
Note that when all widgets in a shell hierarchy have been made
untraversable, they are considered to have lost focus. When a widget in
this hierarchy is made traversable again, it regains focus.
XmIsTraversable may return unexpected results when widget or its ances-
tors are overlapped by their siblings.
widget Specifies the ID of the widget
Returns True if the widget is eligible to receive focus through key-
board traversal; otherwise, returns False.
XmGetVisibility(3) and XmProcessTraversal(3).