This script allow you to copy keys or group of keys in the graphEditor simply by draging theme.
This script as to be used as a Maya shortcut in combination of "dragCopyKeyPressRelease".
To use it:

1 copy the two script "NP_copyDragKeyPress.mel" and "NP_copyDragKeyRelease.mel" into your /maya/scripts folder.
2 open maya
3 create a shortcut with the following line and the option set to "press".
  source NP_copyDragKeyPress.mel;
4 And create the same shortcut with the following line but this time with the option set to "release".
  source NP_copyDragKeyRelease.mel; 
