bigbluebutton-Github/bigbluebutton-html5/app/client/views/sharedTemplates.html

<template name="makeButton">
  {{#if isMobile}}
    <button type="submit" id="{{id}}" class="{{btn_class}} btn" {{isDisabled}}>
      <i class="{{i_class}}"></i>
    </button>
  {{else}}
    <button type="submit" id="{{id}}" class="{{btn_class}} btn" {{isDisabled}} rel="{{rel}}" data-placement="{{data_placement}}" title="{{title}}">
      <i class="{{i_class}}"></i>
    </button>
  {{/if}}
</template>