All note windows created by Stickies app (http://www.zhornsoftware.co.uk/stickies/) are incorrectly grouped on the same desktop. Note a window rule is needed first to force VirtuaWin to manage the windows. This issue seems to be caused by a regression in v4 and caused by the windows have a hidden owner window.
Fix submitted to CVS and will be in the next release (v4.4)