Proposal: use of xdg-shell popups outside of xdg-shell

[Drew DeVault]

Hi there! Over at the wlroots project we're thinking about repurposing
xdg-shell popups for use in another protocol that needs popups. The
popup interface is somewhat complex and duplicating it for each protocol
that might want to support popups is less than ideal.

>From an API perspective, both xdg positioner and xdg popup look easily
reused with parents other than xdg toplevel. Everything is cleanly
separated in xdg shell to accomodate for this. The only real issue is
this line:

https://github.com/wayland-project/wayland-protocols/blob/master/stable/xdg-shell/xdg-shell.xml#L1010

I propose simply dropping this comment from the protocol description.
It's a backwards- and forwards-compatible change, and there's no
compelling API-driven reason not to permit the reuse of xdg popups
elsewhere. Would definitely simplify the implementation of our new
protocol and future protocols that could use them.

--
Drew DeVault