Documentation updates for STR #2142 (protected draw methods).

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6665 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 10 insertions, 1 deletions

diff --git a/FL/Fl_Widget.H b/FL/Fl_Widget.H
index 46e457833..8d6e57005 100644
--- a/FL/Fl_Widget.H
+++ b/FL/Fl_Widget.H
@@ -177,8 +177,17 @@ public:
       Never call this function directly. FLTK will schedule redrawing whenever
       needed. If your widget must be redrawn as soon as possible, call redraw()
       instead.
-    
+
       Override this function to draw your own widgets.
+
+      If you ever need to call another widget's draw method <I>from within your
+      own draw method</I>, e.g. for an embedded scrollbar, you must downcast the
+      embedded widget's pointer to Fl_Widget* and call the virtual draw() method.
+
+      \code
+        Fl_Widget *s = &scroll;		// scroll is an embedded Fl_Scrollbar
+	s->draw();			// calls Fl_Scrollbar::draw()
+      \endcode
    */
   virtual void draw() = 0;