you can't slide the top of the window off the screen
You can use "move" in the system menu. Once activated, the arrow keys in the keyboard will move the window outside the desktop window, not sure if you can do it using the mouse somehow.
You can also use Win+Up arrow key to maximize the window, from there you can grab the title bar to drag it somewhere (preferably inside the desktop this time).
You can use "move" in the system menu. Once activated, the arrow keys in the keyboard will move the window outside the desktop window, not sure if you can do it using the mouse somehow.