Run the "jQuery UI Sortable - Portlets Demo" and try swapping "ui- icon-minusthick" for "ui-icon-plusthick", and you will notice that it only seems to see the "ui-icon-minusthick" part of the image. This appears to be the case for any pairing of icons where the second icon appears to the right of the first icon in the ui-icons_*.png file.
- [jQuery] possible jQuery ui icon bug jim
- [jQuery] Re: possible jQuery ui icon bug Richard D. Worth