Tray icon still white with Windows light theme

[krnkktz]

Client version: Version 2.4.3 (build 10188) on Windows 10 1903

With the Windows 10 1903 update, a new light theme is available. When using monochrome icons with the light theme on, the dark systray icons should be used. Instead, the systray icon remains white on a light background and is unreadable.

If my understanding of the code is correct, implementing hasDarkSystray_private to detect the theme should solve the issue.

To reproduce:
Under Owncloud > General, set "Use Monochrome Icons".
Under Windows 10 Settings > Personalization > Colors, set "Choose your color" to "Light".

[michaelstingl]

Client version: Version 2.4.3 (build 10188) on Windows 10 1903

Please check with latest stable 2.5.4:
https://owncloud.org/download/#owncloud-desktop-client-windows

[krnkktz]

Reproduced with 2.5.4 (build 11415) (understandably, see theme.cpp and utility_win.cpp).