As I just mentioned in a reply to my original bug report, I am testing Beta5 right now with my original document and the sample 1-page document I sent to you. Based on your advice, I started in the LG breakpoint and set each of the 3 columns to Infinity (via right sidebar Infinity icon click), then I opened the MD breakpoint, then SM, and then XS and did the same change in each breakpoint. Only then did all 3 columns fill the width of the row, with each being precisely 1/3 the width of that row. So basically, as you told me in the bug report, if you don’t make the same Column width = Infinity in all breakpoints, the Column width won’t get set to Infinity. Saying it another way, setting the Column width to a fixed value like 12 in XS prevents you from setting that same Column to Infinity in LG or MD. But that is a problem for the reason I will explain below.
Can I please be allowed to hold down the Option key and click the Infinity Icon to set the width of a selected Column to infinity and have that change applied to all breakpoints? That will avoid a lot of unnecessary manual labor.
When you start with 3 side-by-side columns in LG (I always start designing in LG), you almost always want each Column to take up 1/3 the width of the row they are in. Actually, by default those 3 columns are already set to Infinity, which is a good thing. Having 3 columns set to Infinity width usually works well for the MD breakpoint too, so no changes are usually necessary in MD. But for SM and XS, the content of each of those 3 columns in many cases would become too small to look good, so the only option is to set each Column to 12 (in MD and XS) so that each of the 3 Columns fills the entire row width. That won’t look bad at all in MD and XS because the display width is narrow. However, the BIG PROBLEM with setting each column to 12 in MD and XS is that it messes up the width of those 3 columns in LG and MD. You no longer can set all 3 columns to Infinity width in LG and MD because you have set their width to fixed values in SM & XS. The end result is you end up with one of the 3 columns being wider than the other two (in LG and MD), and it looks unbalanced and wrong. That was the basis for me discussion this issue, so if there is a way to remedy this, it will be a rich design blessing indeed!
SUMMARY: I want Infinity width for each of my columns in the same row in LG and MD, but I want a fixed Column width in SM and XS, for reasons already explained.