An 8x6px textless tooltip shows up after you D&D a link from one browser window to another, at least for the steps to reproduce below. 1) open two browser windows, and position them so that they are partially overlapped 2) Load http://us.imdb.com/Title?0120570 into the window on the right. 3) Scroll down to the list of actors. 4) Drag one of the actor links from the right browser window, and drop it into the left browser window. (Do not move the mouse any further). Actual results: Small, textless tooltip appears at end of page load, usually a few inches up from the mouse position. This is almost 100% reproducible for me on win2k with an opt. trunk build pulled Saturday evening. Expected results: Don't show the tooltip. This is possibly related to the timer changes (both the low-level changes and the changes to nsXULTooltipListener.cpp that I made). I don't think there is anything wrong with the changes I made, but this may be exposing a bug with timers (famous-last-words-what-blame-me?). [Also, this may possibly have something to do with the random tooltip crashes that have been reported for Mac OS/X and BeOS (although not reported on win32 or linux, to my knowledge)]. I'll try to look further at this when I have time.

this also happens on linux-qt :)