avoid GTK "assertion `min < max' failed"

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39200 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/scrolbar.cpp

@@ -182,6 +182,12 @@ void wxScrollBar::SetThumbPosition( int viewStart )
 
 void wxScrollBar::SetScrollbar(int position, int thumbSize, int range, int pageSize, bool)
 {
+    if (range == 0)
+    {
+        // GtkRange requires upper > lower
+        range =
+        thumbSize = 1;
+    }
     GtkAdjustment* adj = ((GtkRange*)m_widget)->adjustment;
     adj->value = position;
     adj->step_increment = 1;