Right-click on row headers

Once you right click on the row headers you will see the context menu:

Here you can quickly:
A - Test the selected item. See: Testing multiple classes/teachers at once
B - Open dialogs for item's details, time-offs, constraints, lessons and in case of classes also divisions. You can also open print preview with timetable for this selected item only.
C - Open verification dialog with all inputted constraints. You can quickly check for broken constraints or card relationships linked to specified item. Using "stars" or "colors" can help you by marking items for easier identification.
Verify just one class/teachers/subject
D - In the last area you can remove all cards, or lock/unlock all cards already placed in selected row.
Locked cards