Launcher icon labels do not update when the dashboard is opened

[Kevin Jadin]

Ubuntu Natty x64
Unity Version : 3.6.8-0ubuntu3

When the dash is closed and we put the mouse over an icon, a label displays the program name horizontally.
This label updates itself if the mouse leaves the icon.

When the dash is opened, this doesn't happen anymore.

Steps to reproduce:
1) Open the dashboard
2) mouse over an icon
3) move the mouse vertically without leaving the dock
=> the application name label does not update itself as it should
If we want it to update, the cursor has to leave the dock first and then come back to the icon