In the Angular material dialog, md-dialog-actions is up.

<md-dialogaria-label="Post Question"ng-clock>
  <form>
    <md-toolbar>
      <div class="md-toolbar-tools">
        <h2>Post Question</h2>
        <span flex></span>
        <md-button class="md-icon-button"ng-click="cancel()">
          <md-icon md-svg-src="img/close.svg" aria-label="Close dialog">/md-icon>
        </md-button>
      </div>
    </md-toolbar>
    <md-dialog-content style="max-width:800px;max-height:810px;">
      <div class="md-dialog-content">
        <md-input-container>
          <label>Title</label>
          <inputng-model="question.title"md-autofocus>
        </md-input-container>
        <md-list>
          <md-subheader class="md-no-sticky">Selections</md-subheader>
          <md-list-itemng-repeat="selection in question.selection">
            <div class="md-list-item-text" layout="column">
              <md-input-container>
                <label>Selection {{$index}}</label>
                <inputng-model="selection.content">
              </md-input-container>
            </div>
          </md-list-item>
        <div layout="row">
          <span flex></span>
          <md-button class="md-icon-button"ng-click="addSelection()">
            <md-icon md-svg-src="img/add_box.svg" area-label="Add Selection">/md-icon>
          </md-button>
        </div>
      </div>
    </md-dialog-content>
    <md-dialog-actions layout="row">
      <span flex></span>
      <md-buttoning-click="post(question)" style="margin-right:20px;">Post</md-button>
    </md-dialog-actions>
  </form>
</md-dialog>