Breaks a ‘FireFox Colour’ theme, despite preferences

[ELLIOTTCABLE]

I've selected “Other Theme” in the settings (might want to mention that this is necessary in the AMO page, by the way — I was surprised to find this extension even had settings, while I was writing up this Issue.), but the URL-bar-changing addon still disables the FireFox-Colour-theme I have selected.

With only all extensions except this extension Tree Style Tabs, and FireFox Colour disabled (this reproduces without TST, too; but it's much less obvious, so I chose to leave TST enabled for the screenies), here's what my browser looks like. Note the pattern in the background.

Now, when I open an HTTP page; note that the pattern disappears:

Thereafter, this appearance persists after I switch away from the insecure tab; for the duration of my using the browser, until I reboot it:

Let me know if you need any other information from me!