A long time ago, toolbars automatically stacked below each other when opened. Then came r9796 and the movable menubar. Now toolbars don't automatically stack aymore (which, for some people, was a good thing).
This patch adds this behaviour back. It takes menubar position into account and can be toggled off in the display settings.
That was stacking any window which had not remembered coordinates. I changed it a little.
Also, the stacking works only for the first time. I changed that as well in r11765.
It would be nice, if they would search for a matching hole too, once some hole is above a toolbar ...