Width of frames can be set either as: 1. relative to paragraph area or 2. relative to page width.
I propose to add the third option: relative to the page width minus page margins. This is distinct from paragraph area width as in the case if there are more than one column.
In other words, I want to set frame width relative to the summary width of all columns plus the space between columns.
Probably we also should have "relative to section width".
For example now I edit a document with a two-column section. I want an figure to be of the width of the entire section, not just the width of one of the two columns.
Nice idea Victor
One problem is, that there exist no position values, that refer to the section or to a section column. All existing position values refer to page or to paragraph or, in case of anchor to/as character, to character. So if you would have a relative width/height based on section width/height, you were not able to position the image or frame relative to the section.
Having a customize base for the relative width/height is tracked in issue https://issues.oasis-open.org/browse/OFFICE-3854