Discovery
While dragging a file in the Finder, I accidentally crossed over my contact list, then entered the Dock (configured to autohide on the right side of the screen), then returned through the Dock to the desktop.
Symptoms
The highlighting (purple background with blue ring) around the contact passed over remains. It cannot be removed by hiding and then redisclosing the enclosing contact folder, nor does highlighting any user by selecting them from the contacts list remove the highlighting. The highlighting also remains through changes in the user's status (e.g., from away to available), getting info on the user, and double-clicking to open a new message window.
When more than one user is so highlighted and one such user's status changes (I believe it was an update in the reported minutes idle that triggered this both time I saw it; I am not sure about other sorts of status changes), the highlighting drops from all but the affected user.
No output relating to this appears in either the Console or the debug window.
Workaround
The persistent highlighting can be removed by initiating a file drag and drop, targeting the user, and then backing out without going through the Dock.
Reproducing to the Extreme
This problem can be exploited to "tag" all users with drag-drop target highlighting.
- Drag a file from the Finder over a user.
- While over the user, move right far enough to trigger the Dock.
- Once the Dock is beneath the file, move through the Dock till over the next user.
- Move left till the Dock recedes.
- Trigger the Dock again and continue.
It is as if one were "threading" the file through the contacts list and the Dock. The attached image illustrates the end result of this.
