// Get tool ribbon
var ribbon = workbookBox.getRibbonView();
// Get the Home tab
var mainCatView = ribbon.getMainCategory();
// Get the Series Tree button
var dataSourceButton = mainCatView.getDataSourceButton();
// Display menu of the Series Tree button
var menu = dataSourceButton.getMenu();
menu.show();
// Get source tree
var seriesTreeList = mainCatView.getSeriesTreeList();
// Process the DisplayTreeChanged event
mainCatView.DisplayTreeChanged.add(function (sender, eventArgs) {
    console.log("The DisplayTreeChanged event is initiated");
});
// Output source tree identifier
console.log("Source tree identifier: " + seriesTreeList.getId());
// Hide menu of the Source Tree button
menu.hide();