Regression caused by revision 27874. This bug is only noticed when the session size is bigger than browser window, the viewport, on a touch device and one actives the "hand" option to pan. To reproduce one has to either disable the automatic resize (on the server side) or invoke a different resize, such as one by xrandr -s.
(In reply to comment #0) > Regression caused by revision 27874. Reopen bug 4642 instead?
Revert r28261 when fixing this.
I have reworked the viewport logic in noVNC to make this work and pushed the changes to a upstream pullrequest: https://github.com/kanaka/noVNC/pull/271 I will give some other noVNC people a few days to review the code before merging it into noVNC master and before I do the vendordrop for ThinLinc.
Fixed in commits 29968 and 29969. r29968 - vendordrop r29969 - revert r28261
r29970 - Enable the automatic resize feature by default in thinlinc
Pans just fine now. Tested with Firefox on Android.