Create a overlay that will display over all of the other slide content.
Editing the overlays
Right click an overlay and click "Edit" to open the overlay in the "Edit" page. This can be edited the same way as any other slide.
Displaying an overlay
Click on an overlay in the drawer to display it in the output. If you change it you have to refresh the output for the changes to display in the output. The overlays can also be dragged onto any show slide, and will then be played when the slide is played.
Right click an overlay and click "Lock to output" to enable the lock. All the locked overlays will not be cleared when the "Clear all" button is pressed, and they will remain in the output even when the program is restarted. The can be toggled on/off individually by clicking on them in the drawer.
In the overlays tab, there is a section called "Variables". Here you can currently create either text, or number. Use them to easily change the number or text value in any variable item, on any slide. Most commonly used for a score counter.