Monty

I am selecting regions within a sample, stored in a buffer, via a waveform display and then patching the start & end points from the waveform display selection start & end outs to a groove object.

Great! I have a nice looping window to play with.

Is it now possible to adjust the buffer size to match the new start & end points defined within the waveform display, so as to further edit & process my selected region?

waveform-display-region-to-defiine-buffer-size

Subtract the third output from the fourth (selection start ms.-selection end ms.) this will of course give you the figure you need .

if i got you right, you are looking for the "crop" message to 

if i got you right, you are looking for the "crop" message to  
[waveform].
it's in the help file.
v

waveform display region to defiine buffer size