I can't believe nobody caught this problem that affects vector, but
not monobook skins.

It's so simple to reproduce.
In Firefox visit
http://en.wikipedia.org/wiki/Main_Page
Now start hitting CTRL++ or ALT v z i, to zoom in, making fonts bigger
for older users.

Observe how the "Main Page" "Discussion" "View Source" tabs start
overprinting and getting truncated, etc.

Now restore sizes with CTRL+0 and try again with
http://en.wikipedia.org/wiki/Main_Page?useskin=monobook
See, all fine in monobook. No such bug.

Seen with Mozilla/5.0 (X11; Linux i686; rv:2.0b7) Gecko/20101111 Firefox/4.0b7 Iceweasel/4.0b7

Created attachment 7914
jumble

Here I have hit CTRL++ many more times than usual, to better show the problem.
Note in monobook, the same amount of CTRL++'s at most only cause the globe logo to move over some text. The tabs maintain their proper appearance.

Attached:

(In reply to comment #1)

I can't believe nobody caught this problem that affects vector, but
not monobook skins.

Far from it, I rigorously test this exact behavior constantly, and am following our documented guidelines.

http://www.mediawiki.org/wiki/User_interface_guidelines#Design_Considerations

Yes, if you have a really small monitor the tabs may overlap. To help with this, a JavaScript powered extension causes tabs to collapse into a drop-down menu when there's not enough room.

You are seeing that if the text scales REALLY big (larger than 200% or it's original size) and the user's screen is REALLY small (lower than 800px wide) there's an issue. So - yes, that's true. But it's already known and accepted.

Ideas for how to solve for this edge case are welcome.

200%?! All I know is "Read" becomes "d" upon even the very first hit
of CTRL++, starting from a CTRL+0 state, here on my 7 inch EEEPC 702
at resolution 800x480. I also know that monobook gets it right.