2000511 - [KDE 5.x] Address bar frozen on drag

Status: UNCONFIRMED

(Core :: Widget: Gtk, defect)

Description

[val1337]

Attachment: 2025-11-17 16-14-15.mkv

Steps to reproduce:

Dragging tab around address bar.

1. Startup firefox
2. Drag tab then move cursor very quickly down. (see video attached below)

See Also: (similar threads i've tried searching)
https://bugzilla.mozilla.org/show_bug.cgi?id=1955112&GoAheadAndLogIn=1
https://bugzilla.mozilla.org/show_bug.cgi?id=1955112&GoAheadAndLogIn=1

Actual results:

Address bar frozen (all UI buttons cease to function) for that tab

Expected results:

Tab should follow cursor and be rearranged.

Comment 1

[val1337]

About:support information

Application Basics
Name Firefox
Version 145.0
Build ID 20251106194447
Distribution ID
Update Directory
/usr/local/lib/firefox
Update History
Update Channel release
User Agent Mozilla/5.0 (X11; Linux x86_64; rv:145.0) Gecko/20100101 Firefox/145.0
OS Linux 6.8.0-87-generic #88-Ubuntu SMP PREEMPT_DYNAMIC Sat Oct 11 09:28:41 UTC 2025
OS Theme Breeze / Adwaita
Application Binary /usr/local/lib/firefox/firefox-bin
Profile Directory
.mozilla/firefox/1aealo4l.Default User1234
Build Configuration about:buildconfig
Memory Use about:memory
Performance about:processes
Registered Service Workers about:serviceworkers
Multiprocess Windows 1/1
Fission Windows 1/1 Enabled by default
Remote Processes 9
Enterprise Policies Inactive
Google Location Service Key Found
Google Safebrowsing Key Found
Mozilla Location Service Key Found
Safe Mode false
Memory Size (RAM) 61.9 GB
Disk Space Available 417 GB
Profiles about:profiles

Comment 2

[Thinker Li [:sinker]]

Thanks for the detailed report with the video. To help debug this address bar freeze issue, could you please run Firefox with drag-and-drop logging enabled and share the output?

Please run:

MOZ_LOG=WidgetDrag:5,WidgetDragService:5 firefox 2>&1 | tee drag_debug.log

Attach the drag_debug.log file to this bug.

This will help us understand where the drag operation state is breaking down and causing the address bar to freeze. The WidgetDrag and WidgetDragService logs may show us the exact sequence of drag events leading up to the freeze.

Comment 3

[Martin Stránský [:stransky] (ni? me)]

Which desktop / version do you run?
Thanks.

Comment 4

[val1337]

(In reply to Thinker Li [:sinker] from comment #2)

Thanks for the detailed report with the video. To help debug this address bar freeze issue, could you please run Firefox with drag-and-drop logging enabled and share the output?

Please run:

MOZ_LOG=WidgetDrag:5,WidgetDragService:5 firefox 2>&1 | tee drag_debug.log

Attach the drag_debug.log file to this bug.

This will help us understand where the drag operation state is breaking down and causing the address bar to freeze. The WidgetDrag and WidgetDragService logs may show us the exact sequence of drag events leading up to the freeze.

Thanks for the quick response! Let me know if you require another video. https://gist.github.com/valr337/202c24ab0786cacc6bd7032ce0789a8c

(In reply to Martin Stránský [:stransky] (ni? me) from comment #3)

Which desktop / version do you run?
Thanks.

145.0, Kubuntu / Wayland, downloaded from https://www.firefox.com/en-US/browsers/desktop/linux/

Comment 5

[Martin Stránský [:stransky] (ni? me)]

Which KDE version do you run?

Comment 6

[val1337]

uname -a
Linux 6.8.0-87-generic #88-Ubuntu SMP PREEMPT_DYNAMIC Sat Oct 11 09:28:41 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

neofetch shows
OS: Kubuntu 24.04.3 LTS (Noble Numbat) x86_64

Edit: ignore the paste above, file wasnt properly saved
https://gist.github.com/valr337/41e94854ef9f19d61e451c07d101f9dc#file-debug_log_2-txt

Comment 7

[Martin Stránský [:stransky] (ni? me)]

Looks like Kubuntu 24.04.3 LTS uses KDE Plasma 5.27.12 which has this Wayland D&D bugs. Please update to Plasma 6.x line (6.5).

Comment 8

[val1337]

Without any major tinkering, the next widely available release that has Plasma 6 is Kubuntu 25.10. A full upgrade to a non-LTS release just for a newer desktop environment would inevitably break countless packages on my system.

Besides, Kubuntu 24.04 LTS was released just last year with the explicit purpose of providing a stable, consistent foundation. A major version upgrade is overkill / not viable for many users.

Comment 9

[Martin Stránský [:stransky] (ni? me)]

(In reply to val1337 from comment #8)

Without any major tinkering, the next widely available release that has Plasma 6 is Kubuntu 25.10. A full upgrade to a non-LTS release just for a newer desktop environment would inevitably break countless packages on my system.

Besides, Kubuntu 24.04 LTS was released just last year with the explicit purpose of providing a stable, consistent foundation. A major version upgrade is overkill / not viable for many users.

As it's recognized bug on KDE we can't fix that in Firefox itself.