Empty grids shouldn't take any space

[avernet]

Empty rows don't take space (#2414), but it seems empty grids do take space.

+1 from customer

[avernet]

Is this a regression? I'm wondering as this seems to be covered by the title of #2414 which mentions the grids themselves in addition to grid rows. The space is created by a margin-bottom: 10px on .xbl-fr-grid, and somehow, while the grid is "empty", the margin collapsing doesn't happen. However, it does happen when manually removing the table.fr-grid inside the div.xbl-fr-grid.

[ebruchez]

I don't know if it's a regression or not.

[avernet]

I'd expect margin collapsing to kick in, but it doesn't when the blocks contain a table. I must be missing something here. I suspect there is a very simple explanation (and hopefully a simple workaround as well), so I asked the question on Stack Overflow.

[avernet]

The table creates a block formatting context, so each table is in a different block formatting context. Now it seems that this also causes each container div to be a in different block formatting context, and margin collapsing only happens amongst blocks that are part of the same block formatting context.

I haven't found a way to prevent the table from creating a block formatting context, so instead, I removed the margin on the grid, and added a padding on sections (except the first), so we have some space between the last grid in a section and the next section. This isn't exactly the same as before, as now we don't have the 10px between grids, but it can be argued that is is better in some (most?) cases, in particular when consecutive grids aren't logical units but instead used to align controls.

[avernet]

To reproduce the issue, paste the source of form.txt in Form Builder.