Specifying size="1" for a non-themed popup makes long options wrap and make the popup taller when they're selected. See attached test case.
Created attachment 11158 [details] Test case
I noticed this bug in the Web Inspector's tree popup.
html4.css has the following: keygen, select { ... white-space: pre; } select[size], select[multiple], select[size][multiple] { ... white-space: initial; } select[size="0"], select[size="1"] { ... /* no white-space declaration */ } white-space should probably be set to pre again in the more specific case of size="0" or size="1". Doing this in the stylesheet without !important would still allow the author to have popups wrap. I'm not sure you want to allow that.
Created attachment 13977 [details] Fix html4.css Also added missing border-radius to the 'select' rule and cleaned up a little.
Comment on attachment 13977 [details] Fix html4.css r=me
Landed in r20857.