Partial fix for HTML5 drag and drop with collection views.

Reviewed by me.

AppKit/CPCollectionView.j

@@ -590,6 +590,14 @@
 
 - (void)mouseDragged:(CPEvent)anEvent
 {
+    var locationInWindow = [anEvent locationInWindow],
+        mouseDownLocationInWindow = [_mouseDownEvent locationInWindow];
+
+    // FIXME: This is because Safari's drag hysteresis is 3px x 3px
+    if ((ABS(locationInWindow.x - mouseDownLocationInWindow.x) < 3) &&
+        (ABS(locationInWindow.y - mouseDownLocationInWindow.y) < 3))
+        return;
+
     if (![_delegate respondsToSelector:@selector(collectionView:dragTypesForItemsAtIndexes:)])
         return;