ERROR: unknown attribute/path - control.dragfriction

Hi,

I'm unable to set the parameter control dragfriction, I've tried both using an action and via the control element, I always get the same error:
ERROR: unknown attribute/path - control.dragfriction

I'm using version 1.19 of the viewer, can anybody help ?

Thanks for your answer, I think it would be good if this is mentioned in the xml reference.

The error has disappeared, but I'm still having trouble getting the viewer to behave the way I want, I would like to do something similar to the facebook viewer, when releasing after drag the photo continues to rotate for a bit, here's what I tried with no success:

<control mouse="drag"
touch="drag"
draginertia="0"
dragfriction="1"
/>

I've tried higher values for dragfriction too, but it doesn't seem to change much.