The web-item styleClass element seems to only be applied in some cases, and not others. It's missing from items in the "gg" shortcut "Find Actions" dialog.

See the attached screenshots for an example.

As a workaround we have hooked into the dynamically generated "aui-list-item-li-X" class, which in Gliffy's case is called "aui-list-item-li-add-gliffy-diagram". However, the problem with this is that the class is inconsistent across languages since it's dynamically generated using the web-item label element. Thus, the work around only works for English currently.