Band in Rebar isn't properly repainted

Testcase and .exe included.

Replication method#1:

• Click in "Options" -> "Show toolbar" to hide the Toolbar
• Then click in "Options" -> "Show toolbar" to show the Toolbar again

Replication method#2 (even easier):

• Resize the window, as soon as you do it, the toolbar is not repainted correctly.

Result: The Band in the Reband is not properly painted until forcing invalidation.

Not sure if I_Kill_Bugs can help with his knowledge in repainting issues