The only reason for separate files is Objective-C callbacks into Go,
or when the Go side is common, yet the Objective-C side differs from
macOS to iOS.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Package wm (for "window manager") is a better fit for the package, and
distinguishes it from the low-level package windows for the Windows API.
Signed-off-by: Elias Naur <mail@eliasnaur.com>