Can I alter the frame rate of an animated GIF by script?

[Graham Samuel]

Still trying out non-animated GIF animations (haven't tried PNG yet). I've 
followed various listers suggestions by changing the icon of a button to 
show successive frames of an animation, using the construct

  send "showNextFrame" to me in 150 milliseconds

to loop around a collection of 30 frames (the handler showNextFrame being 
in the button itself).

This works very well, except I'm getting some strange speed anomalies. 
Doubtless these are my fault, but can anyone say how accurate this type of 
timing is likely to be? I expected the interval to be longer than I 
requested at times (if the machine was sufficiently busy) but so far I'm 
seeing apparently much **shorter** iterations appearing after low hundreds 
of frames have been shown, averaging well under 100ms. Like I said, it's 
probably me, but has anyone else seen this kind of thing? I'm running on 
Windows XP.

TIA

Graham

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Graham Samuel / The Living Fossil Co. / UK & France