My problem: sometimes I forget to review published interviews for a talk. I publish a weekly interview series, the 'PostgreSQL Person of the Week' interviews. The data lives in a big spreadsheet, which has several sub-sheets. My idea was to color the background of this cell, based on the value in the first sheet: make the cell background green when the interview is completed. This gives me an instant indication if I need to work on this interview or not. Turns out this is a bit complicated, but possible.