When drawing with a tablet, if the cursor leaves the canvas, then the canvas doesn't receive anymore the tablet events. This is a Qt bug, most likely related to http://trolltech.com/developer/task-tracker/index_html?method=entry&id=168641 . The problem lies in QApplication::notify , since "hasMouseTracking()" is ignored in case of a tablet. There is a workaround in Krita for now (but as all workaround, it's not good enough), krita will generates a fake tablet release events when the tablet leave the canvas, unfortunately, there is a Qt bug, and the canvas only get the leave event when the cursor is released.
SVN commit 934914 by berger: Sounds like the tablet tracking issue has been fixed upstream in 4.5.0. So I disable the workaround for Qt < 4.5.0. This still need confirmation before closing the bug report. CCBUG:162874 M +2 -0 kis_qpainter_canvas.cpp WebSVN link: http://websvn.kde.org/?view=rev&revision=934914
I confirm the situation is improved with 4.5RC1, the hack isn't needed anymore, unfortunately, it seems like when the table is outside, we only receive release events, and not move events, which still make coming back on the canvas lets a line appears.
Didn't lukas' canvas work fix this, too?
I think that yes, this has been fixed by infinite canvas. Now events are generated in the whole canvas.
Ok, then let's close the bug.