Time in Events Schedule cannot be changed back to NULL

[Ken McLean]

Time in Events Schedule cannot be changed back to NULL. If I enter a Time and decide it's wrong, I cannot change it back to being blank (or NULL)

[Craig Mahony (cmahony)]

Done and committed to Cranbourne branch.

[Craig Mahony (cmahony)]

Fix committed to main branch.

[Ken McLean (kenmclean)]

This has been fixed, but there are related bugs that make it not work.

Two related bugs are occuring:

1. When you remove time by backspace (not delete), hitting tab or enter removes the time, but takes the new time to the newly focused cell. However when you press tab/enter AGAIN, it goes back to the time that it originally was, because:
2. You cannot change a time from one value to another. It just reverts back to the old time.

Steps to replicate

1. Events > Schedule
2. Give half a dozen events a time, eg. 1,2,3,4,5,6
3. Edit the "1" time, and remove time using the backspace key.
4. Press tab or enter. The cell "2" will now have focus, but will contain the text "1"
5. Press tab or enter. The cell reverts back to "2"
6. Change the cell "3" to "9"
7. Press tab or enter. The cell reverts back to "3"