diff --git a/packages/oncoprintjs/src/js/oncoprint.js b/packages/oncoprintjs/src/js/oncoprint.js
index 670d6a4dd4c..1b7dc3d1c34 100644
--- a/packages/oncoprintjs/src/js/oncoprint.js
+++ b/packages/oncoprintjs/src/js/oncoprint.js
@@ -638,14 +638,17 @@ var Oncoprint = (function () {
             return;
         }
         this.keep_horz_zoomed_to_fit = this.keep_horz_zoomed_to_fit && still_keep_horz_zoomed_to_fit
-        // Update model
-        this.model.setHorzZoom(z);
-        // Update views
-        this.cell_view.setHorzZoom(this.model);
-        this.minimap_view.setHorzZoom(this.model, this.cell_view);
 
-        executeHorzZoomCallbacks(this);
-        resizeAndOrganizeAfterTimeout(this);
+        if (this.model.getHorzZoom() !== z) {
+            // Update model if new zoom is different
+            this.model.setHorzZoom(z);
+            // Update views
+            this.cell_view.setHorzZoom(this.model);
+            this.minimap_view.setHorzZoom(this.model, this.cell_view);
+
+            executeHorzZoomCallbacks(this);
+            resizeAndOrganizeAfterTimeout(this);
+        }
         return this.model.getHorzZoom();
     }
 
diff --git a/packages/oncoprintjs/src/js/oncoprintwebglcellview.js b/packages/oncoprintjs/src/js/oncoprintwebglcellview.js
index eba5b4198d3..41555a16298 100644
--- a/packages/oncoprintjs/src/js/oncoprintwebglcellview.js
+++ b/packages/oncoprintjs/src/js/oncoprintwebglcellview.js
@@ -198,13 +198,12 @@ var OncoprintWebGLCellView = (function () {
                     return;
                 }
                 clearOverlay(self);
-                self.highlightHighlightedIds(model);
 
                 var offset = self.$overlay_canvas.offset();
                 var mouseX = evt.pageX - offset.left;
                 var mouseY = evt.pageY - offset.top;
+                var overlapping_cells = model.getOverlappingCells(mouseX + self.scroll_x, mouseY + self.scroll_y);
                 if (!dragging) {
-                    var overlapping_cells = model.getOverlappingCells(mouseX + self.scroll_x, mouseY + self.scroll_y);
                     var overlapping_data = (overlapping_cells === null ? null : overlapping_cells.ids.map(function(id) {
                         return model.getTrackDatum(overlapping_cells.track, id);
                     }));
@@ -232,6 +231,8 @@ var OncoprintWebGLCellView = (function () {
                     last_cell_over = null;
                     cell_over_callback(null);
                 }
+
+                self.highlightHighlightedIds(model, overlapping_cells ? overlapping_cells.ids : []);
             });
 
             self.$overlay_canvas.on("mousedown", function(evt) {
@@ -760,7 +761,6 @@ var OncoprintWebGLCellView = (function () {
 
     OncoprintWebGLCellView.prototype.highlightColumn = function(model, uid, opt_track_id) {
         if (uid === null) {
-            clearOverlay(this);
             return;
         }
         var left = model.getZoomedColumnLeft(uid) - this.scroll_x;
@@ -1072,11 +1072,13 @@ var OncoprintWebGLCellView = (function () {
         this.highlightHighlightedIds(model);
     }
 
-    OncoprintWebGLCellView.prototype.highlightHighlightedIds = function(model) {
+    OncoprintWebGLCellView.prototype.highlightHighlightedIds = function(model, opt_exclude_ids) {
         // Highlight highlighted ids
         var highlightedIds = model.getHighlightedIds();
         for (var i=0; i<highlightedIds.length; i++) {
-            this.highlightColumn(model, highlightedIds[i]);
+            if (!opt_exclude_ids || opt_exclude_ids.indexOf(highlightedIds[i]) === -1) {
+                this.highlightColumn(model, highlightedIds[i]);
+            }
         }
     }