added comment

src/main/java/edu/mit/blocks/codeblockutil/CHoverScrollPane.java

@@ -55,7 +55,11 @@ public class CHoverScrollPane extends CScrollPane implements KeyListener {
     private int thumbWidth;
     private Workspace workspace = null;
    
-    /**workspace zoom settings */
+    /**workspace zoom settings 
+    * match with 
+    *   com.ardublock.ui.listener.ZoomInButtonListener and
+    *   com.ardublock.ui.listener.ZoomOutButtonListener
+    */
     private static final double WORKSPACE_MIN_ZOOM = 0.6;
     private static final double WORKSPACE_MAX_ZOOM = 3.0;
     private static final double WORKSPACE_ZOOM_STEPSIZE = 0.1;