Update:
Great News!!!
Found a reverted patch in mypaint git repository that greatly reduced the ghost line problem on my n900 without disabling pressure sensibility:
http://gitorious.org/mypaint/mypaint...a842a25904a6fd
The patch above was reverted due to problems with external drawing pads (that report location without pressure events) our screens need the pressure event to report the new drawing location.
Updated packages links in the first post.
Yes - it works better now... Finally!