I'm using 8.5.6 on Mac OSX 10.3.9 on an old iMac G3. I have an app with a listbox, and I've noticed that the listbox reports (and highlights) the wrong entry after I have moved the app window. Initially, if I have not moved the window, the aim is correct, but afterwards the wrong entry is highlighted and reported. It looks as if there is a mapping between screen coordinates relative to the origin of the app window and absolute coordinates, and that mapping gets lost when the window is moved. I have a small test of this which I'm attaching.