[GREG3\]KILL
KILL calls the interactive cursor to interact with the current IMAGE
buffer. The buffer must have been loaded in write mode (IMAGE /WRITE).
Recognised keys are:
- V to give the value of the pixel,
- K to give the current blanking value to the pixel,
- I to interpolate the value from the neighbour pixels,
- E to exit from interactive cursor mode.
Any other key is ignored.