Based on
http://qelectrotech.org/bugtracker/view.php?id=27

--- krita/plugins/paintops/dynadraw/dyna_brush.cpp.orig	2010-03-01 14:09:15.020748609 +0000
+++ krita/plugins/paintops/dynadraw/dyna_brush.cpp	2010-03-01 14:12:55.340751702 +0000
@@ -188,7 +188,7 @@
         qreal screenX = m_mouse.velx * m_image->width();
         qreal screenY = m_mouse.vely * m_image->height();
         qreal speed = sqrt(screenX * screenX + screenY * screenY);
-        speed = qBound(0.0, speed , m_circleRadius * 2.0);
+        speed = qBound((qreal)0.0, speed , m_circleRadius * (qreal)2.0);
 
         drawCircle(painter, prev.x(), prev.y() , m_circleRadius + speed, 2 * m_circleRadius  + speed);
         //painter.paintEllipse(prevl.x(), prevl.y(), qAbs((prevl - prevr).x()), qAbs((prevl - prevr).y()) );