Windows OS: Resize the browser window by dragging the top or left borders. Quit and relaunch. The first window opened is sized correctly, but its position is incorrect: it's unchanged and it should have been changed. When a border is dragged, Windows doesn't send us a WM_MOVE event; only WM_WINDOWPOSCHANGED. The current WM_WINDOWPOSCHANGED handler makes note of only the new size, not the new position, assuming a WM_MOVE is on the way. Losing that assumption will fix the problem but causes a bit of inefficiency and risks infinite recursion as the movement feeds back on itself. It's fixable but minor and a little dangerous. This bug is what remains of morphed bug 86955, now properly unmorphed and closed.

Note this bug happens to be fixed by the patch in bug 203590.