ratpoison@earthmk2:~$ cvt 1440 900 75
# 1440x900 74.98 Hz (CVT 1.30MA) hsync: 70.64 kHz; pclk: 136.75 MHz
Modeline "1440x900_75.00"  136.75  1440 1536 1688 1936  900 903 909 942 -hsync +vsync
ratpoison@earthmk2:~$ xrandr --newmode  "1440x900_75.00"  136.75  1440 1536 1688 1936  900 903 909 942 -hsync +vsync
ratpoison@earthmk2:~$ xrandr --addmode VGA-0 "1440x900_75.00"X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  33
  Current serial number in output stream:  34