title: EXTJS tree panel disable selection change
body: <p>I have tree panel:</p>
  
  <pre><code>        xtype : 'treepanel',
          itemId : 'field-tree-command-metas',
          region : 'center',
          hideHeaders : true,
          rootVisible : false,
          emptyText : 'No Commands Available',
          deferEmptyText : true,
          bufferedRenderer : false,
          reference : 'treeCommandMetas',
          bind : {
              selection : '{bindSelection}'
          },
          listeners : {
              boxready : function() {
                  var treeView = this.getView();
                  treeView.refresh();
              }
          },
          columns : [ {
              xtype : 'noicontreecolumn',
              dataIndex : 'name',
              flex : 1,
              nodeIconsProvider : function(record) {
                  if (record.isLeaf()) {
                      return [ '&lt;i class="' + Glyphs.getIconClass('square-o', 'size-14px') + '"&gt;&lt;/i&gt;' ];
                  }
  
                  if (record.isExpanded()) {
                      return [ '&lt;i class="' + Glyphs.getIconClass('folder-open-o', 'fa-lg') + '"&gt;&lt;/i&gt;' ];
                  }
  
                  return [ '&lt;i class="' + Glyphs.getIconClass('folder-o', 'fa-lg') + '"&gt;&lt;/i&gt;' ];
              }
          } ],
          displayField : 'name',
          store : 'Plugin.scheduler.store.CommandMetaStore'
  </code></pre>
  
  <p>On form loaded in this tree a record is selected.
  Is it possible to disable other selections? I mean that if something in tree is selected, user cannot change selection.
  Tried 'disableSelection:true' but it disables all selections, I would like selection made by default visible.</p>