Add transparency to systray

[PMunch]

Describe the bug
When I implemented transparency for the statusbar I didn't realize that the systray was a separate window. This means that the systray doesn't get transparency applied to it if you set the transparency option for the statusbar.

To Reproduce
Set transparency for the statusbar, open a program which adds itself to the systray.

Expected behavior
The entire status bar, including the systray, should become transparent with the transparency setting.

Additional context
Should be super easy to fix, just apply the changes here: 6497800 to the systray window as well. I'm mostly creating this issue as a reminder to myself. But if anyone else gets it done before me I won't complain.