diff --git a/gtk2_ardour/editor_drag.cc b/gtk2_ardour/editor_drag.cc
index caa807de3d..41044a4577 100644
--- a/gtk2_ardour/editor_drag.cc
+++ b/gtk2_ardour/editor_drag.cc
@@ -4240,8 +4240,7 @@ SelectionDrag::motion (GdkEvent* event, bool first_move)
 		}
 		
 		/* select all tracks within the rectangle that we've marked out so far */
-		TrackViewList to_be_added_to_selection;
-		TrackViewList to_be_removed_from_selection;
+		TrackViewList new_selection;
 		TrackViewList& all_tracks (_editor->track_views);
 
 		ArdourCanvas::Coord const top = grab_y();
@@ -4249,27 +4248,28 @@ SelectionDrag::motion (GdkEvent* event, bool first_move)
 
 		if (top >= 0 && bottom >= 0) {
 
+			//first, find the tracks that are covered in the y range selection
 			for (TrackViewList::const_iterator i = all_tracks.begin(); i != all_tracks.end(); ++i) {
-			
 				if ((*i)->covered_by_y_range (top, bottom)) {
-					to_be_added_to_selection.push_back (*i);
+					new_selection.push_back (*i);
 				}
 			}
 
-			//add any tracks that are GROUPED with the tracks we selected
-			TrackViewList grouped_add = to_be_added_to_selection;
-			for (TrackViewList::const_iterator i = to_be_added_to_selection.begin(); i != to_be_added_to_selection.end(); ++i) {
-				RouteTimeAxisView *add = dynamic_cast<RouteTimeAxisView *>(*i);
-				if ( add && add->route()->route_group() && add->route()->route_group()->is_active() ) {
+			//now find any tracks that are GROUPED with the tracks we selected
+			TrackViewList grouped_add = new_selection;
+			for (TrackViewList::const_iterator i = new_selection.begin(); i != new_selection.end(); ++i) {
+				RouteTimeAxisView *n = dynamic_cast<RouteTimeAxisView *>(*i);
+				if ( n && n->route()->route_group() && n->route()->route_group()->is_active() ) {
 					for (TrackViewList::const_iterator j = all_tracks.begin(); j != all_tracks.end(); ++j) {
-						RouteTimeAxisView *rem = dynamic_cast<RouteTimeAxisView *>(*j);
-						if ( rem && (add != rem) && (rem->route()->route_group() == add->route()->route_group()) )
+						RouteTimeAxisView *check = dynamic_cast<RouteTimeAxisView *>(*j);
+						if ( check && (n != check) && (check->route()->route_group() == n->route()->route_group()) )
 							grouped_add.push_back (*j);
 					}
 				}
 			}
 
-			//now compare our list with the current selection, and add or remove as necessary  ( most mouse moves don't change the selection so we can't just SET it for every mouse move; it gets clunky )
+			//now compare our list with the current selection, and add or remove as necessary
+			//( NOTE: most mouse moves don't change the selection so we can't just SET it for every mouse move; it gets clunky )
 			TrackViewList tracks_to_add;
 			TrackViewList tracks_to_remove;
 			for (TrackViewList::const_iterator i = grouped_add.begin(); i != grouped_add.end(); ++i)
@@ -4278,10 +4278,8 @@ SelectionDrag::motion (GdkEvent* event, bool first_move)
 			for (TrackViewList::const_iterator i = _editor->selection->tracks.begin(); i != _editor->selection->tracks.end(); ++i)
 				if ( !grouped_add.contains ( *i ) )
 					tracks_to_remove.push_back ( *i );
-					
 			_editor->selection->add(tracks_to_add);
 			_editor->selection->remove(tracks_to_remove);
-			
 
 		}
 	}