Richard M. Stallman wrote:

>    Sorry, forgot to write that it is the code in `mouse-drag-window-above' 
>    that looks suspicious to me. It seems like it only compares the top of 
>    the parameter window with the bottom of other windows.
>
>Yes, it is finding a window whose bottom is at the same height
>as the top of this one.
>
>Are you saying it might find the wrong window?  It could find a window
>that ends at the same vertical position as the right window, but is
>located to the side of it?
>
>I am not sure if that bug can occur.  Can you add code to
>verify that the window found overlaps in the horizontal dimension
>with the given window?
>  
>
I have attached a patched where I believe I have done that.