Don't show empty tooltip in GtkTreeView
I came across this problem when installing the Whisker Menu Widget from Xfce. When I hover the mouse over certain menu entries then there is an empty tooltip visible. The menu is generated with .desktop files. If these files don't have a comment field or a comment field with an empty string then we get the empty tooltips. Please have a look at this screenshot:
At the Xfce Bugtracker they said they cannot fix this issue and it's an issue with the GtkTreeView. Here is the link to the original bug report at Xfce.