449680 - Unhiding menuitems in popup menus causes it to jump in certain circumstances

Status: NEW

(Core :: XUL, defect)

Description

[Ian Neal]

Steps to reproduce:
1/ Have a popup menu that comes up near the bottom of a window.
2/ Have a hidden item in the menu.
3/ Position the window close to the bottom of the screen so that when the menu pops up with item hidden it still pops down from the mouse cursor.
4/ Have a onpopupshowing function that unhides the item in the menu.

Expected result
1/ The menu knows it has a hidden item and assumes it will be unhidden so pops the menu above the mouse cursor rather than below.

Actual result
1/ The menu pops up below the mouse cursor and then jumps above the mouse cursor as the item is unhidden (on first showing).

This was spotted during work on the proxy status popup menu on bug 444157

Comment 1

[[e-mail]]

I've observed the reverse effect too i.e. the popup opens above the cursor but after the popupshowing code hides an item it flips below now that it has room.