Tabs in qbittorrent are completely transparent

[LenaTDDS]

When using "darkly" in the "Application Style", tabs in qbittorrent become completely transparent, which shines through to the window that is behind it (or the desktop wallpaper). At the same time, "darkly" settings have not changed in any way, and by default all 3 parameters are set to 100% opaque. It hurts eyes a lot:(

[DeltaCopy]

What is the active color scheme ?

When using the Breeze Dark the toolbar and menubar all look consistent.

[LenaTDDS]

What is the active color scheme ?
https://github.com/ddh4r4m/Amethyst

There really is no such problem with breeze dark, but if I use a combination of color scheme - amethyst and any application style other than darkly (for example, breeze), then there is no such problem.

It's not very obvious to me yet what the problem is.

[DeltaCopy]

Darkly renders the toolbar background with a transparent area (providing the color scheme supports transparency) whereas Breeze does not do this.

A better idea would be to add a setting which allows the user to override this behavior.
Just like we have opacity settings for the menu, sidebar, menubar add one potentially for toolbar.

[DeltaCopy]

Toolbar settings added as part of #112
Initial testing by adjusting the opacity seems to be working as expected in Kate, Dolphin, qBitorrent, Akregator.
Although it may need further testing.