gboolean gtk_widget_get_hexpand_set ( GtkWidget* widget )
gtk_widget_set_hexpand() has been used to
explicitly set the expand flag on this widget.
If hexpand is set, then it overrides any computed expand value based on child widgets. If hexpand is not set, then the expand value depends on whether any children of the widget would like to expand.
There are few reasons to use this function, but it’s here for completeness and consistency.