Report #34450

Fix for 2.66a

Some editors in Blender (Like Graph) have "maxzoom" set to 0, which caused the 
MMB zoom sensitivity to be minimal. That used to be much more responsive, restored
it to how it worked before.

source/blender/editors/interface/view2d_ops.c

@@ -1034,10 +1034,11 @@ static int view_zoomdrag_modal(bContext *C, wmOperator *op, wmEvent *event)
 		}
 		else {
 			/* 'continuous' or 'dolly' */
-			float fac, zoomfac = 0.001f * v2d->maxzoom;
+			float fac, zoomfac = 0.01f;
 			
 			/* some view2d's (graph) don't have min/max zoom, or extreme ones */
-			CLAMP (zoomfac, 0.001f, 0.01f);
+			if (v2d->maxzoom > 0.0f)
+				zoomfac = CLAMPIS(0.001f * v2d->maxzoom, 0.001f, 0.01f);
 			
 			/* x-axis transform */
 			fac = zoomfac * (event->x - vzd->lastx);