Not so long ago, on another Windows machine, X opened it's fullscreen root window within a Windows window, allowing me to resize or drag it to partially display both the X root and Windows desktop. This was convenient.
Currently, I am unable to duplicate this behavior: -fullscreen opens without decoration, requiring ALT-TAB to reveal any other windows; -fullscreen -scrollbars (a guess) fails.
Just don't use -fullscreen at all. That opens in the default single window mode that has a title bar that will allow you to drag the window around. -scrollbars should allow you to resize the window in the default single window mode, but it hasn't been tested in a long time, so it may be broken.
Harold
