Vertical tab disappears dragging between windows

[rillian]

Description

Testing vertical tabs on Linux I found it's possible for the tab icon to disappear when dragging it between windows.

This is on Gnome Desktop, Fedora 38, x86_64, focus-on-hover enabled in gnome-tweaks.

Steps to Reproduce

1. Enable vertical tabs
2. Open two windows
3. Press super-leftarrow and super-rightarrow to dock the two windows side-by-side covering the full display
4. Drag a tab from one window to the tab area of the other
5. Wiggle it in and out of the second window

Actual result:

Tab icon/detached window disappears. Releasing the mouse either returns the tab to the original window, or leaves it in a third window hidden behind the other two.

Screencast.from.2023-05-16.15-18-10.webm

Expected result:

Tab should say connected to the pointer until it's released.

Reproduces how often:

So far I can do it reliably

Brave version (brave://version info)

1.52.92 Chromium: 113.0.5672.92 (Official Build) beta (64-bit)

Version/Channel Information:

• Can you reproduce this issue with the current release? No vertical tabs there, I think?
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

Follow-up to testing requests on Linux for #29993

[rebron]

cc: @sangwoo108 @fallaciousreasoning