Message timing problem (was: Re: Can I alter the frame rate of an animated GIF by script?)

[Graham Samuel]

I reported that doing an animation using messages of the form

  send "showNextFrame" to me in 150 milliseconds

seemed to result in faster execution than I had asked for (it is quite easy 
to see this happening on the screen). I've now looked at the 
pendingMessages during one of these overspeed episodes of the animation and 
I find that the messages are scheduled between 3 and 20 milliseconds apart!

I dimly see that I may somehow have activated more than one instance of my 
showNextFrame handler in some strange way - this is the only way I can 
imagine the pendingMessages getting closer together than 0.15 seconds; but 
I still badly need suggestions of what I can have done wrong, and if I have 
called the handler more frequently than my required interval, how I could 
program the handler to reject these additional calls.

TIA

Graham

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