1504525 - Window repainting fails on WIndows 10 with transparent "AccentColor" values

Status: RESOLVED WONTFIX

(Thunderbird :: Untriaged, defect)

Description

[nf-uni]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36

Steps to reproduce:

I manually set the "AccentColor" in the registry on my Windows 10 through an old script.
I noticed that all values for this 32 bit color where the alpha part (high byte) is anything but fully opaque this bug occurs.

The registry key is located at:
HKEY_CURRENT_USER\Software\Microsoft\Windows\DWM

Setting "AccentColor" to 0xFExxxxxx (where 'x' are the existing hex values) will cause the bug upon restarting Thunderbird.



Actual results:

Repaint of the main Window completely fails, by flickering and only managing to draw some UI elements but never the caption (toplevel window).

Comment 1

[Richard Marti (:Paenglab)]

Windows 8 has no AccentColor setting.

Does Firefox behave the same? We use the code from Firefox.

Also note that this is a hack and Windows 10 doesn't support transparent accent colours (my Win 10 VM shows the Explorer titlebars still opaque), at least officially.

Comment 2

[nf-uni]

Interestingly Firefox was not impaired in any way.

Yes that is totally correct, Windows 10 does not support transparency.
The color settings were still in place since early Windows 10 versions did not allow color configuration of the caption bar.
Since the alpha byte has no effect it was just set to 0 in manual configuration which was still in place.

Surely this is not a common issue at all, but since the application goes totally unresponsive I thought it might be worth looking into.