app: support changing Window options at runtime

A Window can now be requested to change its options after
it has been started via its Option method.

All options are supported on macOS, Windows and X11.
On Wayland, only the Size and Title options can be changed
at runtime.

Signed-off-by: pierre <pierre.curto@gmail.com>

app/internal/wm/os_wayland.go

@@ -181,6 +181,7 @@ type window struct {
 
 	mu        sync.Mutex
 	animating bool
+	opts      *Options
 	needAck   bool
 	// The most recent configure serial waiting to be ack'ed.
 	serial   C.uint32_t
@@ -357,7 +358,7 @@ func (d *wlDisplay) createNativeWindow(opts *Options) (*window, error) {
 	C.xdg_surface_add_listener(w.wmSurf, &C.gio_xdg_surface_listener, unsafe.Pointer(w.surf))
 	C.xdg_toplevel_add_listener(w.topLvl, &C.gio_xdg_toplevel_listener, unsafe.Pointer(w.surf))
 
-	w.Option(opts)
+	w.setOptions(opts)
 
 	if d.decor != nil {
 		// Request server side decorations.
@@ -910,6 +911,13 @@ func (w *window) WriteClipboard(s string) {
 }
 
 func (w *window) Option(opts *Options) {
+	w.mu.Lock()
+	w.opts = opts
+	w.mu.Unlock()
+	w.disp.wakeup()
+}
+
+func (w *window) setOptions(opts *Options) {
 	_, _, cfg := w.config()
 	if o := opts.Size; o != nil {
 		w.width = cfg.Px(o.Width)
@@ -1143,8 +1151,10 @@ func (w *window) process() {
 	w.mu.Lock()
 	readClipboard := w.readClipboard
 	writeClipboard := w.writeClipboard
+	opts := w.opts
 	w.readClipboard = false
 	w.writeClipboard = nil
+	w.opts = nil
 	w.mu.Unlock()
 	if readClipboard {
 		r, err := w.disp.readClipboard()
@@ -1163,6 +1173,9 @@ func (w *window) process() {
 	if writeClipboard != nil {
 		w.disp.writeClipboard([]byte(*writeClipboard))
 	}
+	if opts != nil {
+		w.setOptions(opts)
+	}
 	// pass false to skip unnecessary drawing.
 	w.draw(false)
 }