I have found the following solution consistently effective on Windows XP, Windows 7 as well as Windows 8. As mentioned above, have both (or more) applications running simultaneously on separate tabs. "Click" on each application to select them (sequentially) and then "click" the "restore down" button on the immediate left of the red X "close" button. This will produce a variable size window. "Drag" its title bar to the side, activate(select)an underlying window and repeat "restore down" (it looks like a 3D box). Each tab can be re-sized (as described by Alok), by dragging a double pointing arrow which appears when the cursor straddles the right or bottom window boundary. This method will accommodate multiple web browser tabs as well applications like Word, Paint,PDF's etc.