app.xml

<?xml version="1.0" encoding="UTF-8" ?>
<Module>
<!-- 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
-->
  <ModulePrefs title="Click To Talk">
    <Require feature="rpc"/>
    <Require feature="views"/>
    <Require feature="locked-domain"/>
  </ModulePrefs>
  <Content type="html">
    <![CDATA[
    
<script src="//plus.google.com/hangouts/_/api/v1/hangout.js"></script>

<input type=button value="Talk" id="talk" onClick="talk()"/>
	
<script>

// Remember some divs for easy reference later.
var talkButton = document.getElementById('talk');
var currentUserID = null;

function talk() {
  var participants = gapi.hangout.getParticipants();
  
  for (var index in participants) {
    var participant = participants[index];
    if (participant.id !== gapi.hangout.getLocalParticipantId()) {
      gapi.hangout.av.muteParticipantMicrophone(participant.id);
    }
  }
  gapi.hangout.av.setMicrophoneMute(false);
}

// This runs when the gadget is ready
function init() {
  console.log('Init.');

  // When API is ready...
  gapi.hangout.onApiReady.add(
      function(eventObj) {
        if (eventObj.isApiReady) {
            gapi.hangout.av.setMicrophoneMute(true);
        }
      });
}

// Wait for gadget to load.
gadgets.util.registerOnLoadHandler(init);

</script>
    ]]>
  </Content>
</Module>