Hi, My environment is Snow Leopard with Xcode 3.2 with Cocoa framework. My application requirement is that there must be 2 NSWindow which are placed adjacent to each other and attached to each other. One of the windows is movable and when that moves, the 2nd window also moves. the Second window doesnot have a title bar. In the view class of the 1st Window, I am able to track/handle mouse movement on the 1st window (like mouse enter, mouse exit) and other window movement related notifications like windowDidMove, WindowwillMove etc and move the position of the 2nd window such that it is attached to the 1st window. But the movement of the second window is not smooth at all (i mean after I left click on title bar, drag the mouse and release the 1st window will the related window move notification be fired where I draw the 2nd window)and the user experience is quiet awful. Is there a mechanism where I tell the framework that the 2nd window's position is fixed with respect to the 1st window. Alternatively is there a mechanism where I can track the movement of 1st window continuously such that I can smoothly draw the 2nd window. Thanks in advance.