Irregular lesson groups
In addition to periodic lesson groups it is possible to define completely free time patterns.
Open the demo.gpn file, click on 'Data | Lesson groups' and create a lesson group with any name you choose.
Open the school year calendar by clicking on the button of that name.
All the days of the school year are coloured green and thus active.
By moving the cursor while holding the left mouse button you can define interruptions and the colour changes from green to white.
The interruption in the lesson group is then displayed in the form view.