Reuse IZArc Windows determines whether a new window is opened when you start IZArc by double clicking in My Computer, Windows Explorer, or the desktop. When this entry is checked, an existing IZArc window is used. When this entry is not checked, a new IZArc window is created. One advantage to reusing IZArc windows is that double clicking acts the same as drag and drop, and you never accidentally wind up with multiple IZArc windows.