Description of problem:
Unlike other icon image files which have a transparent background, the
/usr/share/icons/crystalsvg/16x16/apps/thunderbird.png and
/usr/share/icons/crystalsvg/32x32/apps/thunderbird.png files have a
white background instead.

Because of this, the icons don't show well on most desktop backgrounds.

I could propose new icon files fixing this, but it's better to let the
 ir creator do it, by generating the icon images from the full-sized
image already with a transparent background. The result will be better
than hacking images shrunk from a white background.

Version-Release number of selected component (if applicable):
3.3.1-4.1

How reproducible:
Always

Steps to Reproduce:
1. gimp /usr/share/icons/crystalsvg/*/apps/thunderbird.png
  
Actual results:
The images have a white background.

Expected results:
They should have a transparent background

Additional info: