Excellent question! There are a few limitations that we have to place on the ConPty to make it work quite right. Primarily, client apps running attached to the conpty will not be able to have separate viewport and buffer sizes. On *nix, the entire "console buffer" is just the size of the window, but on Windows, technically, the buffer is much larger than the window. (as an example, when you open up a command prompt, there's a giant empty space at the bottom if you scroll down). Fortunately, we haven't came across any apps that _need_ the buffer to be a different size than the viewport, and it's a technically valid console configuration, so apps should have been able to support it before.
Input is also tricky - VT doesn't let you express input with as much fidelity as a console app might be expecting, though this we're working on a solution for :)
Now Windows just needs to ship with a decent pager. :-)
Programmatic access to scroll back is useful for a few things. For example, back when I was on Windows Phone, I wrote a compiler wrapper that would scroll back to the first error message.
It'd be nice for the POSIX terminal world to standardize on similar scrollback access. I know the zsh people would love it.
*nix consoles typically have two buffers - many full-screen temrinal applications switch to the "alternate screen" on start and back to the principal screen on exit. That's why when you exit vim(1), you see the terminal state back as it was before you started it. Will ConPty support this?
Yep! It'll probably act a little different than you'd expect - the pseudoconsole itself will switch between the primary and alt buffers, leaving the terminal in the main buffer always. We'll "render" the contents of the alt buffer to the terminal, then when the client app switches back to the main buffer, conpty will re-render the contents of the main buffer to the terminal.
It's not the most elegant solution, but we're still very early in on this project. We still have lots of improvements to be made to the infrastructure and translation, and even as I type this up, I'm thinking there's probably a better way of handling alt buffers.
