app/internal/wm: rename confusing app/internal/window

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>

app/internal/wm/os_unix.go

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// +build linux,!android freebsd openbsd
+
+package wm
+
+import (
+	"errors"
+)
+
+func Main() {
+	select {}
+}
+
+type windowDriver func(Callbacks, *Options) error
+
+// Instead of creating files with build tags for each combination of wayland +/- x11
+// let each driver initialize these variables with their own version of createWindow.
+var wlDriver, x11Driver windowDriver
+
+func NewWindow(window Callbacks, opts *Options) error {
+	var errFirst error
+	for _, d := range []windowDriver{x11Driver, wlDriver} {
+		if d == nil {
+			continue
+		}
+		err := d(window, opts)
+		if err == nil {
+			return nil
+		}
+		if errFirst == nil {
+			errFirst = err
+		}
+	}
+	if errFirst != nil {
+		return errFirst
+	}
+	return errors.New("app: no window driver available")
+}