Friendly user tip:

How to prevent external programs pop up and steal your screen. (such as skype, antivirus or windows updates.. etc.)

Once in game, go to..

Option screen (the kog wheel at the bottom right corner of your game screen) this opens up your Options Menu

Now click on VIDEO options
Find the Windowed Mode (3rd option)
In he drop down menu to the right of that, choose Borderless.
Click ok. Now close the menu.

This will make sure that if anything does pop up, your game remains visible and will not minimize your game screen.