That bug has been described on https://launchpad.net/distros/ubuntu/+source/gnome-panel/+bug/39711

"Steps to reproduce:

1) Press Alt+f2 launch the run dialog
2) Expand the "Show list of known applications" box.
3) Type an application name in the entry box, I used Text Editor.
4) Click on the text entry for "Text Editor"

What I expected to happen:

The entry for Text Editor should be highlighted and I should be able to either to click the run button or double click the name to launch the application.

What actually happened:

The filtering of the the known applications box is cleared and the executable name of gedit is copied to the entry box. If I had double clicked, the Add/Remove entry is launched and I'm surprised to see the package manager launch."