Comment 33 for bug 46801

Ok, I'll try to be as clear as I can at the cost of repeating myself.

Providing smaller icons will not fix the bug without patching the apps.

The workaround used by some apps to avoid the cropping it's a hack that involves overriding the default padding around the icon done by the theme. This fixes the cropping, but breaks other themes and that's why it wasn't integrated upstream in other programs.

Moving to have a single close button out of the tabs (ala firefox) is out of the scope of this bug and definately can not be considered in the current timeframe.
Given the above it's a fact that apps will keep the close button on the tabs right now, so the solution for this bug should take into account that even with the cropping issue solved a colorful orange button on every tab is very distracting and annoying.

I really think that the solution right now should be going back to the old icon or design a new one similar to the old one with sober color.