Its actually a bug in Tk, IIRC. I had a discussion on #tcl about it. I don't remember the detail , here's one descrtipn:

:<jenglish> frame/toplevel/labelframes always make a geometry request whenever you [$w configure] them. If they have a geometry master, it will see the <Configure> event, restart the geometry propagation dance, and settle back to where things were when they started

Which version of Pd-extended are you seeing this in?

.hc

On Dec 12, 2009, at 9:36 PM, Mathieu Bouchard wrote:

there's a problem with «. configure -cursor $::cursor_runmode_nothing», which is probably a bug in Tk or some versions thereof. it resizes the main window several times in a row very quickly, by tiny amounts. I commented out that line in my copy of the code.

...

actually i just replaced it with «if {[. cget -cursor] != "$::cursor_runmode_nothing"} {. configure -cursor $::cursor_runmode_nothing}» and the glitch happens only once instead of anytime I move an object.

_ _ __ ___ _____ ________ _____________ _____________________ ... | Mathieu Bouchard, Montréal, Québec. téléphone: +1.514.383.3801

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Computer science is no more related to the computer than astronomy is related to the telescope. -Edsger Dykstra