By selecting two point in the chart, in the same way of the values invalidation, it is possible to add an event to the chart.
By clicking the Add event button, a window is shown, to insert tags and the description.
Once the operation is confirmed, the event is shown in the chart area. When the mouse cursor enters the event area in the chart (if the corresponding checkbox is selected), a balloon with its detail is shown.
Each event is linked to a note, visible in any notes widget. By deleting the liked note, the event is also removed from the chart. In the same way, it is possible to ad a new note linking a signal to view the event in the correspondin chart.
It is also possible to add an event from a chart widget, with the same procedure of a note creation.