fixed IE bug

src/adapter/saveto.js

@@ -34,6 +34,9 @@ KM.registerToolbarUI( 'saveto', function ( name ) {
         var a = document.createElement( 'a' );
         a.setAttribute( 'download', filename );
         a.setAttribute( 'href', url );
+        a.onclick = function () {
+            alert( "hahaha" );
+        }
         try {
             a.dispatchEvent( new MouseEvent( 'click' ) );
         } catch ( error ) {