Laucher tooltip doesn't scroll

[GPHemsley]

(I hope this is the right place to file this issue.)

For applications that list their windows in the tooltip associated with their launcher icon (available from right-clicking on the icon), there may be more items in the list than there is vertical screen real estate to display them.

In the past (at some point when Unity was included with Ubuntu), the tooltip would come with arrows at the top and bottom that could be used to scroll through the options. Now, however, the tooltip simply gets clipped at the ends, leaving some options unavailable because they are off the edge of the screen.