not able to resize window on dual monitor

[thinking]

hi all

i have a dual monitor environment running latest ubuntu 10.04
i think since the last update of lucid im not able to
resize a window - like firefox or nautilus - to be bigger than one monitor
e.g. given a window on the left monitor
if i grab window on its right lower corner to resize it, its size keeps within the first monitor - i cant create a window with windowsize of both monitors or overlaping the monitors

moving the window around and such works without problems
any hints on how i can resize again?

thx all