Alternate steps to reproduce:
Have mailnews open, showing a folder/newsgroup with a truncated name. Use the context menu to open that folder in a new window. Ensure that the new mailnews window covers the old one so that the mouse is now above the new window. Nudge the mouse slightly, and you get a tooltip from the old mailnews window.
Alternate-alternate steps to reproduce:
Have mailnews open, showing a folder/newsgroup with a truncated name. Position another in-process window (e.g. browser, js console) so that it partially overlaps the truncated name; hover over this other window where the truncated name is, and a tooltip appears.
Alternate steps to reproduce:
Have mailnews open, showing a folder/newsgroup with a truncated name. Use the context menu to open that folder in a new window. Ensure that the new mailnews window covers the old one so that the mouse is now above the new window. Nudge the mouse slightly, and you get a tooltip from the old mailnews window.
Alternate-alternate steps to reproduce:
Have mailnews open, showing a folder/newsgroup with a truncated name. Position another in-process window (e.g. browser, js console) so that it partially overlaps the truncated name; hover over this other window where the truncated name is, and a tooltip appears.