Comment 1 for bug 1068666

after some further research i found a helpful thread in the linux mint forums:
http://forums.linuxmint.com/viewtopic.php?f=208&t=98899

there, user rj.adams mentions a fix on /usr/share/cinnamon/js/ui/messageTray.js that fixes the described issues by replacing (in version 1.4-UP3) line 1710 which reads 'let expandedY = - this._notificationBin.height;' with 'let expandedY = this.actor.height - this._notificationBin.height;'

this seems to be fixed in the current dev-version 1.6.2 like described but i suppose many users are still on the normally installed cinnamon 1.4.

the ones that are brave enough to switch to the currently latest 1.6.2 may want to follow the description found at
http://blog.linuxmint.com/?p=2177
or edit messageTray.js as described earlier.

issue solved so far for me.