Fix the blank line that is supposed to separate the GUID in icon tooltips from everything else
Revert change to IconContainer.lua because Ticket #931 was actually fixed an extremely long time ago
The tooltip is now hidden when you start moving a group
Added some calls to TMW:UnregisterThisCallback() where appropriate
TMW:UnregisterThisCallback() now operates on the correct callback when called after a nested callback has been fired.