Add max-width to select elements in widgets to prevent it overflowing from widget areas.

[iamtakashi]

I find myself adding this frequently and I thought it could be useful to have in _s.

This intends to fix a common issue - the dropdown in the category widget overflows when a blog has a long category name.

[mfields]

This seems like a really good idea to me. A lot of themes will set overflow: hidden; on the sidebar to keep longer items from "breaking out" of it. Select elements containing longer item names will naturally break out of small width containers meaning that they can be hidden. This fixes that! I suggest merge.

[mfields]

This just came up today while I was coding. @iamtakashi what do you think about adding a test case for this to the monster widget too? This way we can be sure to always see that there is a possibility of this kind of thing happening?

[iamtakashi]

@mfields, Yes that's also good idea too because many themers might not have realised this happens quite frequently in the real world. (Put aside the argument, whether having a long category name is good or bad)

And _s will take care of the issue with my suggestion. Win. If there is no strong opinion form anybody, we should merge this.