error window hangs
------------------
Playing with the "hide/show global flaps" keybinding. I move the
pointer over the visible sliver of background so alt-F will work, but
instead I accidentally leave it over a flap. In this circumstance
Alt-F gives me at least 8 error windows (I mean the ones with the
stack trace) - MessageNotUnderStood: removeAccomodationForFlap:.

This is confusing at first. Windows 2 through N appear one on top of
the other and are identical. So I close one and it appears as if
nothing has happened or that squeak has hung. Move the windows around
to find out if there's a stack of them - aha. So I close them all and
continue.

I do this a second time to verify. This time I start clicking Abandon
and squeak quickly goes to 100% CPU and stops responding. It's hard to
rouse it out of this state; when it wakes up I just get more error
windows. I try alt-dot.. now I'm in the emergency evaluator (yay).  I
hit "any other character to restart" (space, and a few others).  No
visible result; CPU still at 100%. Squeak now hung and unresponsive;
quit and restart.

The third time works like the first. Got seven error windows, closed
them without incident. Oh, I got a debug window when I thought I just
dragged the title bar to move one, but put that down as poor aim.

Fourth time: ok I see one way to provoke it. Do the alt-F over flap
trick to get your half dozen error windows along with temporary
unresponsiveness.  Wait to get control back if you like. But now, hit
alt-dot (you think squeak is still not responding, perhaps). BOOM!
Many more error windows, squeak not responding to mouse (although
display still updates). Hammer on alt-dot some more. More error
windows, oh now CPU utilization goes back down but squeak still
unresponsive. Quit, restart.

Squeak is probably doing something obvious here, but it seems to be a
big hole that's easy for a newbie to fall into and fatal.