[@Mahz] I would like to be able to set the width of a column of cells. Ideally to a percentage of the available space.

In the past I had a character sheet that featured two twins, and I wanted both twin to take up exactly half of the screen so that you could compare them side by side. It was kind of a nightmare to get working, and I eventually ended up having to use multiple tables and carefully using the column widening method Roach pointed out. 

Column width seems to be loosely based on the size of the biggest word (Which is why Roach's stretch method for images works) and number of words in a cell, but it's tricky to figure out how to balance it to get a specific column size. 

Edit: If you want to know how I'd like it to work, I think I'd like it so that you determine the size of the top cell to get the column to be the right size. Though it would not be the end of the world if I had to manually tell every cell what size I wanted it to be. something like "Cell=XX%" would be great.