Wbar clobbers overlapping windows with Xorg-7.6

[ales]

I am having a problem with the Wbar.  Any time I slide another window over it, that window does not get redrawn properly.  The Wbar is always under the window, but it is the top window that gets damaged in the overlapping area.

The window stays damaged even after I slide it out of the way of the Wbar.  I can then force it to redraw correctly by obscuring/exposing the damaged areas with another window.

Has anyone seen this kind of behavior?  It is clearly a bug, but what can be done about it?

Here is what I am using:
  Tiny Core 4.7.7
  Xorg-7.6 (replaced Xvesa)
  xf86-video-ati 7.6
  flwm_topside 1.12
  wbar 1.3.3-3