Bug 209514

Version:           4.3.1 (using KDE 4.3.1)
Installed from:    Unlisted Binary Package

While trying to find a usable set of "Stiffness", "Drag" and "Move factor" values for the Wobbly Windows effect, I came accross some combinations of those values that reproducibly trigger a bug where trying to move any window causes this window to go into a state of extreme spinning and endless turning inside out over the whole screen at a very fast speed (sorry, I don't know how to describe it any better). It's *really* fast and totally confusing (it doesn't even look like a window any more), and it doesn't end - the only way to stop it is to press [ALT]+F4 to close the window.

I did some experimenting with the three values, and so far I found out that the trouble seems to lie in too high values of "Stiffness" and "Move factor", while the "Drag" setting doesn't seem to have much effect on whether the bug occurs or not (but it can influence the exact character of the resulting seemingly chaotic movement, as well as whether it appears instantly or needs some time oscillating to full speed after a window movement was initiated). It appears that for any given "Move factor", the bug occurs when the "Stiffness" is above a certain threshold value. For example, for "Move factor" (M) values of 10, 15, 20 and 25, the following "Stiffness" (S) values cause the bug:

__M_|_S________
 10 | never
 15 | above 42
 20 | above 32
 25 | above 26

(Note: very high "Drag" values can also give quite fast and irritating window movements even at lower M and S values, but I wouldn't consider that a bug since in that case the movement does in fact slow down and and comes to a stop eventually, whereas in the case described in this bug report, the opposite seems to be true: the movement becomes faster and more erratic all by its own and never stops.)