Misc:
I didn't want to call this section bugs, but take your pick between design limitations and unusual features.

Scrolling:
Any scrolling action unselects the current cell. So if you scroll then you must reselect a cell before characters are entered. The programme will not crash but will simply beep at you untill a cell is selected.

Up Arrow and Cells not Deselecting:
Hmmm, I'll try to fix this. Although it appears as though every second cell is selected, it isn't. Only one cell is selected and the programme works as normal. It is a cosmetic bug only.