Function for disabled people with hands/fingers problem, who use mouse with two hands. They can not push alt and mouse button in one time.
You can set that Ctrl, Shift or Alt will automatically hold/block for 1,2 or more seconds (depending on the settings) till time the user push mouse botton and then automatically hold till the user finish the action.
Or first alt push befeore mouse click will "ON" command and second in the end of action will "Off" command.
Regards