Bug 393958

Summary: Alt-tab window switching does not work when dragging a link from thunderbird
Product: [Plasma] kwin Reporter: g111
Component: generalAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED NOT A BUG    
Severity: normal CC: oded
Priority: NOR    
Version First Reported In: 5.12.4   
Target Milestone: ---   
Platform: Ubuntu   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description g111 2018-05-07 14:44:07 UTC 
When dragging an URL from inside a mail in thunderbird you cannot switch to another window (e.g. to firefox) with alt-tab to drop the URL there. Alt-tab does not do anything in this case.

I would expect to be able to switch through the window list by alt-tab while dragging the URL. In KDE 5.8 from Kubuntu 16.04 this did work. This issue happens with thunderbird only. When dragging text from kate to gedit and vice versa the switching works. Also when dragging an URL from kmail window switching does work.

How to reproduce:
* open thunderbird and e.g. firefox so that firefox is in the background and thunderbird in the foreground.
* open a mail in thunderbird that contains at least one URL 
* click and drag the URL.
* while dragging the URL try to switch through the window list (in my case by the hotkey alt-tab)

Result:
The windows are not switched.

Expected:
The windows should be switched.
Comment 1 Martin Flöser 2018-05-07 14:59:57 UTC 
Thunderbird is either grabbing keyboard or pointer. Due to that tabbox cannot open.
Comment 2 Oded Arbel 2020-08-21 19:26:55 UTC 
I'm experiencing the same issue with dragging from Firefox. Dragging from any KDE application does not hinder ALT-TAB switching, nor GNOME apps or Google Chrome. Only Firefox and Thunderbird seem to exhibit this issue.

This seems due to Mozilla issue https://bugzilla.mozilla.org/show_bug.cgi?id=1276449 , where the workaround discussed there works for me as well: setting MOZ_USE_XINPUT2=1 in the environment.

This workaround can be deployed by distributions so bugs should be open for each distribution - I understand Fedora has already deployed this workaround.