When i try to rotate cube i added to scene , alt+mouse 1 configuration move the whole unity-editor . On some linux distro, this is general problem for 3d graphic programs which use same combination as like maya
Temporary solution is pressing windows button on keyboard before ALT button , than you can press mouse 1 to rotate object
Solution :
install Compiz Config Settings Manager by :
sudo apt-get install compizconfig-settings-manager
and open it
on filter menu , search for :
Move Window
and near to mouse icon , change ALT-mouse 1 combination to something else , such as alt-shift-ctrl-mouse 1
so , now you can use ALT+Mouse 1 combination for unity3d