After upgrade to 6.4 all icons are 'inactive' - double-click to launch isn't working - I can not even select an Icon. After investigation this seems to happen only because my icons are set in this arrangement: align right top to button in the 3 other combinations they work normally. This bug could be related to #505860 Very bad experience of an upgrade from 6.3.x to 6.4
Merging in with the primary report for this issue, thanks! *** This bug has been marked as a duplicate of bug 497498 ***