code: function(prefPath) {
  			var didRestoreSelections = false;
  			var expanded = window.sessionStorage[prefPath+"expanded"]; //$NON-NLS-0$
  			if (typeof expanded=== "string") { //$NON-NLS-0$
  				if (expanded.length > 0) {
  					expanded= JSON.parse(expanded);
  				} else {
  					expanded = null;
  				}
  			}
  			var i;
  			if (expanded) {
  				for (i=0; i<expanded.length; i++) {
  					var row= lib.node(expanded[i]);
  					if (row) {
  						this._expanded.push(expanded[i]);
  						// restore selections after expansion in case an expanded item was selected.
  						var self = this;
  						this.tableTree.expand(expanded[i], function() {
  							self._restoreSelections(prefPath);
  						});
  						didRestoreSelections = true;
  					}
  				}
  			}
  			return !didRestoreSelections;
  		}
docs: returns true if the selections also need to be restored.