redash/client/app/components/dashboards/add-widget-dialog.html

<div class="modal-header">
  <button type="button" class="close" ng-disabled="$ctrl.saveInProgress" aria-hidden="true" ng-click="$ctrl.dismiss()">&times;</button>
  <h4 class="modal-title">Add Widget</h4>
</div>
<div class="modal-body">
  <p class="btn-group">
      <button type="button" class="btn btn-default" ng-class="{active: $ctrl.isVisualization()}" ng-click="$ctrl.setType('visualization')">Visualization</button>
      <button type="button" class="btn btn-default" ng-class="{active: $ctrl.isTextBox()}" ng-click="$ctrl.setType('textbox')">Text Box</button>
  </p>

  <div ng-show="$ctrl.isTextBox()">
      <div class="form-group">
          <textarea class="form-control" ng-model="$ctrl.text" rows="3"></textarea>
      </div>
      <div ng-show="$ctrl.text">
          <strong>Preview:</strong>
          <p ng-bind-html="$ctrl.text | markdown"></p>
      </div>
  </div>

  <div ng-show="$ctrl.isVisualization()">
      <div class="form-group">
          <ui-select ng-model="$ctrl.query.selected" theme="bootstrap" reset-search-input="false" on-select="$ctrl.onQuerySelect($item, $model)">
              <ui-select-match placeholder="Search a query by name">{{$select.selected.name}}</ui-select-match>
              <ui-select-choices repeat="q in $ctrl.queries"
                                 refresh="$ctrl.searchQueries($select.search)"
                                 refresh-delay="0">
                  <div ng-bind-html="$ctrl.trustAsHtml(q.name | highlight: $select.search)"></div>
              </ui-select-choices>
          </ui-select>
      </div>

      <div ng-show="$ctrl.selected_query">
          <div class="form-group">
              <label for="">Choose Visualization</label>
              <select ng-model="$ctrl.selectedVis" ng-options="vis as vis.name group by vis.type for vis in $ctrl.selected_query.visualizations" class="form-control"></select>
          </div>
      </div>
  </div>

  <div class="form-group" ng-if="$ctrl.isTextBox()">
      <label><input type="checkbox" ng-model="$ctrl.isHidden">&nbsp;Hidden</label>
  </div>
</div>

<div class="modal-footer">
  <button type="button" class="btn btn-default" ng-disabled="$ctrl.saveInProgress" ng-click="$ctrl.dismiss()">Close</button>
  <button type="button" class="btn btn-primary" ng-disabled="$ctrl.saveInProgress || !($ctrl.selectedVis || $ctrl.isTextBox())" ng-click="$ctrl.saveWidget()">Add to Dashboard</button>
</div>