Index: QLPainter.C
===================================================================
--- QLPainter.C	(Revision 17628)
+++ QLPainter.C	(Arbeitskopie)
@@ -98,7 +98,9 @@
 		return;
 
 	setQPainterPen(col, ls, lw);
+  setRenderHint( Antialiasing, x1!=y1 && x2!=y2 );
 	drawLine(x1, y1, x2, y2);
+  setRenderHint( Antialiasing, false );
 }
 
 
@@ -112,16 +114,20 @@
 	// Must use new as np is not known at compile time.
 	boost::scoped_array<QPoint> points(new QPoint[np]);
 
+  bool antialias = false;
 	for (int i = 0; i < np; ++i) {
 		points[i].setX(xp[i]);
 		points[i].setY(yp[i]);
+    if( i!=0 ) antialias = antialias || (xp[i-1]!=xp[i] && yp[i-1]!=yp[i]);
 	}
 
 	if (!isDrawingEnabled())
 		return;
 
 	setQPainterPen(col, ls, lw);
+  setRenderHint( Antialiasing, antialias );
 	drawPolyline(points.get(), np);
+  setRenderHint( Antialiasing, false );
 }
 
 
@@ -152,7 +158,9 @@
 
 	// LyX usings 1/64ths degree, Qt usings 1/16th
 	setQPainterPen(col);
+  setRenderHint( Antialiasing, true );
 	drawArc(x, y, w, h, a1 / 4, a2 / 4);
+  setRenderHint( Antialiasing, false );
 }