alt-right-click in xterm

[Matt Price <matt.price@utoronto.ca>]

hey folks,

On one computer running debian-unstable right-alt-click in xterm gives
e a bracketed arrow pointint down and to the right.  WHen I move the
mouse, the size of the window changes in the direciton the mouse
moves...  

On another system, also running debian-unstable, the same action gives
me slightly different behaviours depending on wherei n the xtemr
window the mouse focus happens to be; so if I'm in the bottom half of
the window, the arrow pointsi n one direction; if I'm in the top half,
it points in another.  

I liket he second style better, as it gives me more flexibility.  

Anyone know what option controls this behaviour?  

thanks,

matt