It's very annoying especially when closing tabs in a browser. If a middle mouse button is pressed to often then you accidentally minimize a browser's window. That's not ok.
To disable window minimizing on middle mouse button, run the following command in terminal:
gsettings set org.gnome.desktop.wm.preferences action-middle-click-titlebar 'none'
To revert it back, run:
gsettings set org.gnome.desktop.wm.preferences action-middle-click-titlebar 'lower'
To disable browser's tab to close on middle click, see: https://superuser.com/questions/113048/how-do-i-prevent-firefox-from-closing-tabs-on-middle-click
You can also to use
xbindkeys. To install it, run in terminal:
sudo apt-get install xbindkeys
Then the next two lines must be placed in
"" #don't do nothing b:2 #mouse button 2
And finally, you must to clear current bindings with
killall xbindkeys and then just execute
xbindkeys to restart it.