base.widget and siblings of its
ancestors for all widgets matching widget.type.
Of the matching widgets, the one that is geometrically closest to
base.widget will be returned.
The general purpose of this function is to find the most likely "action"
widget, relative to another labeling widget. Such as finding a
button or text entry widget, given it's corresponding label widget.gtkTestFindSibling(base.widget, widget.type)base.widgetwidget.typeGtkWidget] a widget of type widget.type if any is found.