1424718 - transient UI (context menu, textbox completion suggestions) are offset upward on the screen causing bogus interactions

Status: RESOLVED DUPLICATE of bug 1423810

(Firefox :: Untriaged, defect)

Description

[Lars Viklund]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Firefox/59.0
Build ID: 20171211105838

Steps to reproduce:

On Ubuntu Linux 16.04 with XFCE4 as the desktop environment, hold the right mouse button to open a context menu, and release the button.

I have not tested this on any other OS or desktop environment.


Actual results:

The menu that opens is shifted upward on the screen by around one item, compared to a context menu in 57 or the xfce4-terminal application, which has the cursor a pixel above the top of the menu when right-clicking.

When the button is released without moving the mouse, the item that's just about under the cursor is activated.

On a regular page, it's the Back action, with a text selection it's Select All, with an input box it's Cut, all rather detrimental to the state.


Expected results:

The menu should open and stay open until dismissed or an additional click is performed on a menu item.

The menu behaves properly otherwise, this seems to be solely an effect of the offset position of the menu compared to a properly opened menu.

As a note, the completion hint popout for a text input field is also shifted upward, obscuring the field itself. That may be related or indicative of the root of the problem.