It's great that we at last have a dark theme, but it's too blue. For everyday work neutral dark grey is much easier on the eyes. InteliJ with Darkula theme is a great example of dark theme done right - neutral background with warmer font palette.

Besides, your sidebar, some popup menus and table headers are already in neutral grey palette (which I believe caused by Mac graphite theme). Maybe it would be easier to design SourceTree theme around that than figuring out how to change menu colors. I think sidebar colors look better than the rest of UI.