Add flexible bands

[gillsonkell]

This isn't a necessity but would be nice.

Basically a way to band like CSS Flexbox.

• The default band width is the whole page within the margins, but can be set otherwise
• Cells can be given pixel, percent, or flex factor widths, but default to a flex factor width of 1 so the width is evenly divided between them
• Gutter amounts are subtracted from cells with a flex factor width first, then cells with specific widths set if necessary

Examples for a printable area of 100:

• Widths: 50%, 50%, gutter: 5 - Result: 47.5px, 47.5px
• Widths 1, 1, 1 (flex factors), gutter: 5 - Result: 30px, 30px, 30px
• Widths 50%, 25px, 1, 1, gutter: 5 - Result: 50px, 25px, 5px, 5px

[NathanaelA]

That shouldn't be terribly hard. However, I think it might cause some confusion as we don't use "px" in the engine and so when it sees say "10" does it treat it as pixels or flex areas. :) But maybe the engine could use something like "1*" or some other code to designate flex areas.

[gillsonkell]

Yeah "1*" might work for flex values or whatever you think!

[beauwest]

I wonder if it'd be better to use some of the same conventions as Flexbox & Grid. In this case use the fr unit maybe?

That way it's at least somewhat intuitive.

[NathanaelA]

Yeah, fr could be it. Thanks Beau.