1696876 - [wayland] PiP window no longer has a shadow making it lack contrast against background

Status: NEW

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

Description

[Kestrel]

Attachment: PiP window contrast comparison with shadowless on the right

STR:

1. Start with MOZ_ENABLE_WAYLAND=1 on Ubuntu 20.10.
2. Visit https://www.youtube.com/watch?v=J3pF2jkQ4vc (blank white video).
3. Open video in PiP window.
4. Place against white background.

Expected:

PiP window has a shadow, making it stand out.

Actual:

PiP window has no shadow, only a thin pale border, making it difficult to see.

X11 and XWayland are unaffected.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=a7f58bb3f814d4cb528da96afc78b68467c61290&tochange=3511277c894242df40937e5569035cf4aa7fe0a2

Regressed by Bug 1683075.

Comment 2

[Robert Mader [:rmader]]

This is likely because we don't use CSD for it. So we either need the shadows from Gtk or draw them ourselves. Emilio, given that you looked into menu shadows before, do you have an idea what could be done here?

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Well, we could make the window bigger, flag it as transparent using GTK, and then use CSS to style around the player on Linux. It seems a reasonable effort tho, it'd be so much nicer to somehow let GTK draw the decorations...