How to move windows that open up offscreen?

I use this approach:

• Use Alt+Tab to switch to the off-screen application.
• Press Alt+SPACE to bring up the system menu (you won't see it because it is off screen)
• Press R to select the "Restore" menu choice to ensure the windows isn't maximized (you cannot move it if it is maximized)
• Press Alt+SPACE again, then M to select the "Move" menu choice.
• Press one of the arrow keys to initiate the movement.
• Now just use the mouse to place the window where you want.

If you are using a non-English version of Windows, the "R" and "M" menu choices will probably be different.

For Windows 7 and later users: +Shift+← or → will move the selected window to the monitor in that direction.

For Windows 10 in order to use the old move the window with the cursor keys trick you need to have the Shift key pressed when you open the context menu from the Task bar.

Info from How To Geek