Well, I found a solution to my problem, but I don't understand it. The 
answer to the subject line appears to be: when you call FrmEraseForm 
before FrmDrawForm.

In my update event handler, that's what I was doing. If I comment out 
the FrmEraseform, everything is fine.

I'm guessing here a bit, but I logged events in Poser, and there's a 
winExitEvent for my form that appears after the update is handled, and I 
think FrmEraseForm is what generates it. But FrmDrawForm apparently 
doesn't generate a corresponding winEnterEvent.

So the sequence goes like this: I'd do my modal dialog, ande when it was 
dismissed, change the list then force an update to redraw the list. The 
update handler would call FrmEraseForm, then FrmDrawForm. That seems 
perfectly benign to me, but it leaves the form, while perfectly visible 
and drawn, in an undrawable state. A subsequent call to LstSetSelection 
triggered the error.

That's as far as I've gotten, but I have to think there's more to it. 
Surely calling FrmEraseForm followed by FrmDrawForm should leave things 
in a ready-to-draw-further state? Am I missing something obvious?

I can fix the bug by removing code, but I'd also like to understand why 
it was a problem, and why this fix works. Any insights/explanations 
appreciated.

Dave Johnson

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