If you have a window open and hold alt + right click,a menu comes up with Minimize ,Maximize on top..etc.
It’s troublesome when you playing games in ubuntu like war3, you may want to do some change on the key combination.
This tutorial will lead you to disable Alt and right click key
First,go to System–>Preferences–>Windows
At Movement key select one item you want:
If select “Control” or “Super”,shortcut key Ctrl and right-click or Super and right-click will instead the function of Alt and right-click