If you click an arrow, entity or any other visual element on the chart, it is briefly highlighted and the corresponding text is selected in the editor. This is useful to quickly jump to a certain element in the chart text.

If you double-click the chart (try the background) you enter Tracking Mode, where the above behaviour becomes permanent. Visual elements are selected just by hoovering above them. You can enter tracking mode also by the ‘T’ button on the Chart pane or by pressing Ctrl+T. If you move around in the text editor, the visual element corresponding to the text around the current cursor position is highlighted.

You can leave Tracking Mode by pressing Escape.