Open new window in remaining space on screen

[robbins]

Sometimes I'll shrink a window with Alt-, leaving a certain amount of space left on the current view of the screen (without scrolling left or right), and it'd be useful to have a keybind that I could toggle to open the next window in that remaining space.

e.g. on the far right in this screenshot

Would it be possible to implement this?

[YaLTeR]

So, like, with the default window width equal to that remaining size?

[robbins]

Yeah, exactly. But toggleable, so that windows open with the normal default-column-width by default, but default-column-width can be modified to be the remaining size (for the next window open) with a keybind.