This thread reminds me of the problem I usually encounter when making a
custom #drawOn: method for a morph.
I have to work through this stage, but the step appears usually a very
sensitive one, leading frequently to a hangup UI.
It is also a hard to debug step (you wont always get the chance to step
into the debugger). 
Maybe it could be made a little bit easier, when writing data to the
Transcript was not so risky ( I know, it is probably not good behavior
to 'show:' something from within a drawOn: method... But...). As an
example of this risk I defined a subclass of RectangleMorph (attached)
with just the line "Transcript cr; show: self bounds printString."
inserted in the #drawOn: method. When opening such a rectangle and
moving it around on the screen, the UI may hang. For me (on windows) it
always hangs when the rectangle touches the Transcript window, and most
of the time I am not able to recover....
This may be something specific to the Transcript, I don't know, but
maybe it is a symptom of something else as well..

Hans

-----Original Message-----
From: Cees de Groot [mailto:cg at cdegroot.com] 
Sent: dinsdag 22 maart 2005 21:34
To: squeak-dev at lists.squeakfoundation.org
Subject: UI hangups

Hi,

I've been experiencing UI hangups ever since I started working with
Squeak-at-the-backend (Seaside, my current P2P stuff, even various Swiki
incarnations I think) - the symptom is always the same: Squeak does not
respond to mouse&keyboard anymore, but the networkings bits still work.

I now have an image with a severe case of this - it'll hangup in as
little as 10 minutes... So I'm getting tired of this, I want to solve
this for once and for all :)

So, my questions:
- What are the possible causes?
- What is a debugging strategy to find out exactly where it goes wrong?


TIA,

Cees

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