If you have two windows and you resize the other and the borders touch they
should snap just like if you had moved the first window next to the second.
Steps to Reproduce:
That would be cool indeed!
Dunno. Resize code is already very complex bcause of partial struts and all kinds of checks, I'm not sure I really want to add more complexity to that code.
This is a feature that I've gotten very used to with Openbox. Managing windows (tiling out a workspace) is made vastly easier with this ability.