1733103 - firefox leaves fullscreen mode, when resized

Status: UNCONFIRMED

(Core :: Widget: Gtk, defect, P3)

Description

[richard.delorenzi]

Attachment: 2021-08-13-12-44-00-382394.png

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

• Tell FF to enter full screen mode e.g. press f in youtube.
• Tell Window manager to exit full-screen mode, but not tell FF.

Actual results:

• Enter full screen mode: Window manager removes title, bar and frame, and resizes window to fill screen. Browser hiders tab-bar, and address bar, maybe web-page changes layout (e.g. you-tube resizes video player to fill window).
• Tell Window-manager to leave full-screen-mode, but not inform browser: Window manager resizes window (back to normal size), adds title, bar and frame. The browser gets re-size event, and erroneously thinks it should not be in full-screen mode.

(Just the last sentence differs from expected)

Expected results:

• Enter full screen mode: Window manager removes title, bar and frame, and resizes window to fill screen. Browser hiders tab-bar, and address bar, maybe web-page changes layout (e.g. you-tube resizes video player to fill window).
• Tell Window-manager to leave full-screen-mode, but not inform browser: Window manager resizes window (back to normal size), adds title, bar and frame. Browser is now still hiding tab-bar, address-bar, site is till showing video in whole-window, but window can be moved and re-sized.

The attached image shows correct behaviour with chrome. It does the correct thing for all other programs (that I have used, and have full-screen-mode) on my system.

This bug will probably show up in any situation where a display screen can change size: screen-rotation, Virtual-machine screen resize, or in this case where the window-manager allows separation of concern: full-screen-mode of app, and window filling the screen.

I had a quick look at the code: It looks like the trigger to enter full-screen is the WM full-screen event. But the trigger to exit full-screen-mode is a resize.
I did not have much time to look. It was last week, so can't remember details. I could not get it to compile, so did not try anything. If there is a docker image that I can use to compile, then I will have another look.

Comment 1

[richard.delorenzi]

OS Debian: 10.10 Buster
WM/Desktop environment: Kde-plasma

Comment 2

[richard.delorenzi]

I don't think this is a KDE specific bug. I think it relates to the full-screen (_NET_WM_STATE_FULLSCREEN ) event or lack of. Firefox is not reacting to it, but instead reacting to a re-size. The problem manifests on KDE plasma, because this window manager allows separation of telling app to be in full-screen-mode, and frame size. It may also manifest in other situations. The bug and fix should not be in KDE specific code. The fix may be in X11 specific code, if it is the only system to support full-screen-mode(I don't know how MS-Windows and MacOS work).

Comment 3

[richard.delorenzi]

Is this bug being looked at? When will it be resolved?

Comment 4

[Darkspirit]

Workaround: Use Picture-in-Picture.

Comment 5

[:gerard-majax]

Is this still an issue for you?