diff --git a/mindplot/src/main/javascript/Designer.js b/mindplot/src/main/javascript/Designer.js
index dc196e7a..b742d73d 100644
--- a/mindplot/src/main/javascript/Designer.js
+++ b/mindplot/src/main/javascript/Designer.js
@@ -118,6 +118,16 @@ mindplot.Designer = new Class({
 
 
             $(document).addEvent('mousewheel', function(event) {
+                var containerCoords = screenManager.getContainer().getCoordinates();
+                if (event.client.y < containerCoords.top || 
+                    event.client.y > containerCoords.bottom ||
+                    event.client.x < containerCoords.left ||
+                    event.client.x > containerCoords.right
+                    ) {
+                    return true;
+                }
+
+                event.preventDefault();
                 if (event.wheel > 0) {
                     this.zoomIn(1.05);
                 }
diff --git a/wise-editor/doc/ConfigParameters.md b/wise-editor/doc/ConfigParameters.md
index 78964e8e..d11bd7ef 100644
--- a/wise-editor/doc/ConfigParameters.md
+++ b/wise-editor/doc/ConfigParameters.md
@@ -25,7 +25,7 @@ An example config may look like this::
 The options are:
 
 * readOnly: Set to true if the viewer should not be able to edit the map.
-* zoom: how much the map should be zoomed.
+* zoom: how much the map should be zoomed. Range: 0.3 - 1.9. 0.3 = largest text.
 * size: size of the map area.
 * viewPort: set this to the same as the size
 * persistenceManager: Classname of a class that extends mindplot.PersistenceManager (see ImplementingPersistence for more info.)