+- MDI: seems to be broken for a more complex application I'm testing.
+ Frame decorations don't draw properly, and a child window doesn't
+ process events properly. So probably we should have an alternative
+ implementation that uses tabs, a la wxGTK. The system menu could
+ be implemented using a pop-up menu that applies to the currently
+ active window.
+
+- Controls in a wxToolBar don't work. Probably due to form layout
+ problems; the workaround is to use a separate panel for controls.
+