preventDefaultAction in canvas-drag on minimap

src/navigator.js

@@ -417,7 +417,35 @@ function onCanvasClick( event ) {
  * @function
  */
 function onCanvasDrag( event ) {
-    if ( this.viewer.viewport ) {
+    var canvasDragEventArgs = {
+      tracker: event.eventSource,
+      position: event.position,
+      delta: event.delta,
+      speed: event.speed,
+      direction: event.direction,
+      shift: event.shift,
+      originalEvent: event.originalEvent,
+      preventDefaultAction: event.preventDefaultAction
+    };
+    /**
+     * Raised when a click event occurs on the {@link OpenSeadragon.Viewer#navigator} element.
+     *
+     * @event navigator-click
+     * @memberof OpenSeadragon.Viewer
+     * @type {object}
+     * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised this event.
+     * @property {OpenSeadragon.MouseTracker} tracker - A reference to the MouseTracker which originated this event.
+     * @property {OpenSeadragon.Point} position - The position of the event relative to the tracked element.
+     * @property {Boolean} quick - True only if the clickDistThreshold and clickTimeThreshold are both passed. Useful for differentiating between clicks and drags.
+     * @property {Boolean} shift - True if the shift key was pressed during this event.
+     * @property {Object} originalEvent - The original DOM event.
+     * @property {?Object} userData - Arbitrary subscriber-defined object.
+     * @property {Boolean} preventDefaultAction - Set to true to prevent default click to zoom behaviour. Default: false.
+     */
+
+     this.viewer.raiseEvent('navigator-drag', canvasDragEventArgs);
+
+     if ( !canvasDragEventArgs.preventDefaultAction && this.viewer.viewport ) {
        if( !this.panHorizontal ){
             event.delta.x = 0;
         }