How to do stack layout (lr-tb)?

[mfaizsyahmi]

I'm trying to create a gallery view where the children populate the top row, and as it fills the width of the first row it moves to the next. Basically a left-to-right top-to-bottom layout. The number of items in a row varies, and should dynamically flow between rows as the parent window gets resized.

Going through the barely-existing widget documentation it doesn't seem like anything of the sort exists. The closest things are:

1. Tables, but they have a fixed column size.
2. group(horizontal=True), but they only ever do horizontal layout, never wrapping around the end of the parent container.

Is there a lr-tb option I can give to a group that would allow the desired layout?

Desired layout:

group(horizontal=True) result:

[mfaizsyahmi]

I will consider recalculating groups of rows and their contents every time the window changes width as a workaround, but the state of the docs is so abysmal right now that I can't figure out how to attach an on-resize handler to the window.