Support multiple, single-column-width Headers in masonry mode

[Nantris]

This would require laying out the other columns in such a way as to leave space next to the single-column-width header.

The intended layout would look something like this:

[Nantris]

Is there some way we can customize the position of the items in the second column to accommodate this? The API seems to lack such a capability from my reading, but I'm hopeful I'm overlooking something.

I'm envisioning something like:

1. Get y-axis position of heading in column 1, eg 200px down
2. Customize item positions in column 2 such that all items at or after the heading will display below the heading, eg something like (basePosition) => basePosition > 200 ? basePosition + headingHeight : basePosition