bug#50424: 27.2; Tab bar button mouse face not clearing entirely

[Juri Linkov]

>> The change below fixes it here, but I've not made sure it does the
>> right thing with different sized margins and so on.
>
> Thanks, I really appreciate your help.  After seeing the result
> of your patch, one question that came up is whether it's possible
> not to change the previously used dimensions?  With enlarged height
> and width, now the buttons are not vertically aligned:

Sorry, actually this question was addressed to Eli
for the commit with the same subject but different hash:
db74a93659 that contains such changes:

- :margin (2 . 0)
+ :margin ,tab-bar-button-margin