Rough in fullscreen mode on montage

web/skins/classic/views/js/montage.js

@@ -317,5 +317,10 @@ function initPage() {
   }
   selectLayout('#zmMontageLayout');
 }
+
+function watchFullscreen() {
+  const content = document.getElementById('content');
+  openFullscreen(content);
+}
 // Kick everything off
 $j(document).ready(initPage);

web/skins/classic/views/montage.php

@@ -206,6 +206,9 @@ if ( canView('System') ) {
             &nbsp;<?php echo translate('Snapshot') ?>
           </button>
 <?php } ?>
+        <button type="button" id="fullscreenBtn" title="<?php echo translate('Fullscreen') ?>" class="avail" data-on-click="watchFullscreen">
+        <i class="material-icons md-18">fullscreen</i>
+        </button>
         </form>
       </div>
     </div>