Bug 452716

Summary:	Firefox window with browser.tabs.inTitlebar = 1 displays shadows even with "Shadows → Size → None"
Product:	[Plasma] Breeze	Reporter:	tustamido
Component:	window decoration	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED DOWNSTREAM
Severity:	normal	CC:	kwin-bugs-null, nate
Priority:	NOR
Version First Reported In:	5.24.4
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description tustamido 2022-04-18 05:05:08 UTC

SUMMARY
In Window Decorations, I use Breeze with disabled shadows (Shadows → Size → None). But I noticed Firefox is still displaying shadows. I'm sure it wasn't until a few days ago. I strongly suspect this is a regression in Plasma 5.24.4, because it was installed 3 days ago.

The better I could track down the issue was to find out the issue is related to Firefox preference browser.tabs.inTitlebar = 1 (in about:config). That preference makes Firefox window to not display titlebar, with buttons like minimize/close being attached next to tab bar. If you change the value to 0 or 2, titlebar is displayed and then window shadows disappear.

This is not a Firefox bug, the issue is reproducible with any version. And as I said, this is a regression, it wasn't that way until recently.

STEPS TO REPRODUCE
1. Disable window shadows in Breeze settings (Window Decorations, edit Breeze, Shadows → Size = None).
2. Open Firefox.
3. Right-click any point over navigation toolbar except address bar and click "Customize toolbar...".
3. On lower left, uncheck "Title Bar" (this is the same as setting browser.tabs.inTitlebar = 1 in about:config).

OBSERVED RESULT
Firefox window has shadows.

EXPECTED RESULT
Firefox window shouldn't have any shadow.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Manjaro
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.3

ADDITIONAL INFORMATION
X11

Comment 1 Nate Graham 2022-04-18 15:34:16 UTC

`browser.tabs.inTitlebar = 1` makes Firefox draw its own window decorations, including window shadows. Hence, it no longer respects the common settings in Breeze. If you want visual consistency, you should avoid apps using "client-side decorations", as they can all draw shadows, titlebars, toolbars etc differently.

Comment 2 tustamido 2022-04-18 16:25:29 UTC

(In reply to Nate Graham from comment #1)

Thanks, reported it to Mozilla. I could use KDE Plasma to hide Firefox titlebar, but the "hide titlebar" feature in Plasma is not actually just *hide titlebar and nothing more*, it has side effects, it ends up removing window borders and the ability to resize window using mouse.

I guess there's no way for Plasma to just hide titlebar without affecting other window properties.

Comment 3 Nate Graham 2022-04-18 16:27:12 UTC

Yeah, "Hide titlebar" really means "Hide all window decorations, which includes the titlebar and shadows." I guess this could be more clearly indicated. You could file a bug report to systemsettings | kcm_kwin_rules about that.