<NME> disable_default_actions.ts
<BEF> /**
 * @license
 * Copyright 2016 Google Inc.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Prevent context menu on right click, as this interferes with other event handlers for right mouse
 * clicks.
 */
export function disableContextMenu() {
  document.addEventListener('contextmenu', (e: Event) => {
    e.preventDefault();
    return false;
  });
}

<MSG> fix(default_viewer): disable default mouse wheel actions (e.g. browser zoom)

<DFF> @@ -14,13 +14,22 @@
  * limitations under the License.
  */
 
+import {registerEventListener} from 'neuroglancer/util/disposable';
+
 /**
  * Prevent context menu on right click, as this interferes with other event handlers for right mouse
  * clicks.
  */
 export function disableContextMenu() {
-  document.addEventListener('contextmenu', (e: Event) => {
+  return registerEventListener(document, 'contextmenu', (e: Event) => {
     e.preventDefault();
-    return false;
+  });
+}
+
+export function disableWheel() {
+  return registerEventListener(document, 'wheel', (e: WheelEvent) => {
+    if (!(e.target instanceof HTMLInputElement)) {
+      e.preventDefault();
+    }
   });
 }

fix(default_viewer): disable default mouse wheel actions (e.g. browser zoom)