title: Kendo Tree List rows hiden in window modal
body: <p>i'm trying to use kendo ui tree list in a bootstrap window modal, thus, i get only the header shown but body is hiden. when i make the tree list in main page evry thing works correctly.
  this is my code : 
  tree list options: </p>
  
  <pre><code>_this.variablesTreeListOptions = {
                  dataSource: {
                      transport: {
                          read: function (e) {
                              _this.$service.read("api/Variable/GetAll")
                                  .then((result: any) =&gt; {
                                      dataArray = result.data;
                                      gridData = new kendo.data.ObservableArray([]);
                                      gridData.push.apply(gridData, dataArray);
                                      e.success(gridData);
                                  }, (error: any): any =&gt; {
                                      alert("Error");
                                      e.error();
                                  });
                          },
                          parameterMap: function (options, operation) {
                              if (operation !== "read" &amp;&amp; options.models) {
                                  return { models: kendo.stringify(options.models) };
                              }
                          },
                          schema: {
                              model: {
                                  id: "VariableId",
                                  fields: {
                                      VariableId: { type: "number", editable: false, nullable: false },
                                      Code: { type: "string", editable: false, nullable: false },
                                      Libelle: { type: "string", editable: false, nullable: false },
                                      Valeur: { type: "number", editable: false, nullable: false },
                                      Expression: { type: "string", editable: false, nullable: false },
                                  }
                              }, expanded: true
                          }
                      }
                  },
                  sortable: true,
                  editable: true,
                  columns: [
                      { field: "Code", title: "Code", width: "150px" },
                      { field: "Libelle", title: "Libelle", width: "150px" },
                  ]
              }
  </code></pre>
  
  <p>here is my html modal:</p>
  
  <pre><code>&lt;!-- Modal --&gt;
  &lt;div class="modal fade" id="myModal"  aria-labelledby="myModalLabel"&gt;
      &lt;div class="modal-dialog" role="document"&gt;
          &lt;div class="modal-content"&gt;
              &lt;div class="modal-header"&gt;
                  &lt;button type="button" class="close" data-dismiss="modal" aria-label="Close"&gt;&lt;span aria-hidden="true"&gt;&amp;times;&lt;/span&gt;&lt;/button&gt;
                  &lt;h4 class="modal-title" id="myModalLabel"&gt;Générateur de formule&lt;/h4&gt;
              &lt;/div&gt;
              &lt;div class="modal-body"&gt;
                     &lt;div class="col-lg-6 col-md-6 col-sm-6"&gt;
                   &lt;div class="x_panel custom-modal"&gt;
                       &lt;div  kendo-tab-strip k-content-urls="[ null, null]"&gt;
                           &lt;ul&gt;
                               &lt;li class="k-state-active"&gt;&lt;h6&gt;Variables&lt;/h6&gt;&lt;/li&gt;
                               &lt;li&gt;&lt;h6&gt;Rubriques&lt;/h6&gt;&lt;/li&gt;
                               &lt;li&gt;&lt;h6&gt;Formules&lt;/h6&gt;&lt;/li&gt;
                           &lt;/ul&gt;
                                  &lt;kendo-tree-list k-options="vm.variablesTreeListOptions"&gt;
  
                                  &lt;/kendo-tree-list&gt;
                           &lt;div&gt;
                               &lt;div class="x_panel"&gt;
  
                               &lt;/div&gt;
                           &lt;/div&gt;
                           &lt;div&gt;
                               &lt;div class="x_panel"&gt;
  
                               &lt;/div&gt;
                           &lt;/div&gt;
                       &lt;/div&gt;
                   &lt;/div&gt;
               &lt;/div&gt;
                  &lt;div class="col-lg-6 col-md-6 col-sm-6"&gt;
                      &lt;div class="x_panel"&gt;
                          &lt;form&gt;
                              &lt;div class="form-group"&gt;
                                  &lt;label for="formule"&gt;Formule:&lt;/label&gt;
                                  &lt;textarea id="formule" class="form-control"&gt;&lt;/textarea&gt;
                              &lt;/div&gt;
                          &lt;/form&gt;
                &lt;/div&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
              &lt;div class="modal-footer"&gt;
                  &lt;button type="button" class="btn btn-default" data-dismiss="modal"&gt;Fermer&lt;/button&gt;
                  &lt;button type="button" class="btn btn-primary"&gt;Enregister&lt;/button&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>