Icons for Split Button lists stopped showing in 1.3.0 for IE 7. This worked in 1.2.1. See screenshots:
Thanks for reporting the issue. The icons are there but the background is gone, so you don't see them.
I changed background to background-color while working on making it easier for people to use the alt icon color or no icon disc (background). Now we run into this IE7 bug http://css-tricks.com/ie-background-rgb-bug/ that I wasn't aware of. Will fix it for 1.3.2.
I will commit a fix for this to master and cherry-pick into 1.3-stable for 1.3.2.
The issue won't be fixed if you use the ui-icon-alt class, like described here in the "Black vs. white icon sets" section. (Update: This means on IE7 icons have the same background color as when you don't use that class.)
If I would change background-color to background it would override the icon background-position for each icon, because the selector of the rule that sets the background color is more specific than the ones that sets the background image position. Of course I could increase the specificity of those selectors but that would break custom icons. So that's not something we can do in a maintenance release.
Theme: Use shorthand for background color fallback to make it work on…
… IE7. Fixes #6002.
Note: The issue won't be fixed if you use ui-icon-alt. See comment at #6002 in the issue tracker.
Merge branch 'master' into next
Note: Fix for #6002 not applied while merging in the 1.4 "next" branch, because IE7 became C-grade.