@varnuke Which device are you trying to do this on?
Normally when the app opens on a different screen you would drag the window (by the title bar) to the screen that you intend to use it on.
If you are trying to use the UX582LR, you can either:
a) using the track pad - click and drag the title bar of the window to the other screen, or,
b) using your finger on the touch screen - tap and drag the title bar of the window such that the symbol meny appears next to your finger, hover your finger over the menu option you want and then let go with your finger. This can be used to send windows between the screenpad+ and the main screen when using the touch screen only.