Created an attachment (id=7906) [details]
Screenshot of addon bar

As you can see in screenshot (1) addon bar is black, you can't change default
colours (painting mode changes nothing). Also when you use context menu and
hover any item, text turns white (screenshot: http://i.imgur.com/B1DKl63.png ).
I am using Ubuntu Linux

The default of the Bar is translucent (using the background color from your OS
theme) You can disable this by unchecking the box

Bling my Tabs > Appearance > Toolbar Background [x] transparent  

The default colors for ACtive Tab color are taken from the system and should be
the same as that of a selected menu item. You can however select a preset from
the Active Tab Color popup (using Standard Palette or Pastel Colors" or using
"2 Colors" and select background / text color with the color drop downs. I will
attach a newer version for more (and more stable) color choices.

Created an attachment (id=7907) [details]
3.15 - prerelease 290

More stable coloring options are provided with this version, also a new palette
called "Night vision". 

Notes: 

# Do not use the palette options "like inactive tabs" these are unreliable

# Default colors are often not ideal, it is better to select colors for each
status on "bling my tabs" individually

# For consistent fonts in Linux on the Current Folder Panel (displayed center
screen, between thread panel and mail preview) you have to set an explicit
button font size (recommended: 14) in "Bling my Tabs" options.

Created an attachment (id=7908) [details]
3.15 prerelease 293

apparently, in Linux the rule

-moz-appearance: toolbar

for toolbars somehow overrides any styling on the toolbar affecting background
colors or borders, which makes the toolbar always transparent.

I have added a platform specific style sheet for Linux which overrides this to
-moz-appearance: none

this way we can style the toolbar as desired. It would be interesting to see if
this behaves the same way on MAC IOS.

Version 293 fix this problem