Describe the rectangle type and the declared argument types
A popup's rectangle is of the exported type rectangle now, which the API
reference and Popups name. Errors says that SBCL checks the declared
argument types on entry, with the message it gives, and warns of a
constant of the wrong type as it compiles a call.
Follow cl-windowing 031159f: Windows, popups, input methods, cursors, the clipboard
Add pages for popups, input methods, cursors and pointer modes, the
clipboard and the Win32 backend. Bring the others up to date: the Win32
backend beside Wayland, fullscreen and set-window-size, copy-event and the
new event fields and types, the new capabilities and conditions, the
protocols the Wayland backend uses now, and the backend protocol's new
generic functions, reporting functions and lock rules. CI runs the suite
on SBCL only.
