Uder the specific situation:
Using a debian 8.1 to host another debian 8.1 with VirtualBox 5.0.20,
and XFCE 4.10, When I roll down the mouse wheel inside browser, netbeans and possibly any other application the screen fails to do long rolls, possibly a bug with the workspace manager, perhaps signaling that is to change the xfce workspace instead of just rolling down the screen of the app. The fact is that the roll fails. May be a minor bug, but is really annoying.