Numbers... can't enter a cell
I have a spreadsheet with multiple spreadsheets and all was working well until suddenly, on only one of the sheets, I can't enter a cell. When I click anywhere it draws a box around the entire sheet, almost as if I was in drawing mode. No problem getting rid of the box (just click anywhere outside of it) but still can't use my spreadsheet/.
What am I doing wrong... what did I enter by mis