io/system: add ActionInputOp to register window move gesture areas

The app.Window.Perform(ActionMove) is the wrong abstraction for
initiating a move gesture: Windows needs to know the move gesture
area at pointer move, and macOS needs to know the pointer button
down event that triggers the move gesture. This change replaces
Perform(ActionMove) with a new system.ActionInputOp that marks an
area movable.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/os_wayland.go

@@ -879,6 +879,14 @@ func gio_onPointerButton(data unsafe.Pointer, p *C.struct_wl_pointer, serial, t,
 			w.resize(serial, edge)
 			return
 		}
+		act, ok := w.w.ActionAt(w.lastPos)
+		if ok && w.config.Mode == Windowed {
+			switch act {
+			case system.ActionMove:
+				w.move(serial)
+				return
+			}
+		}
 	case BTN_RIGHT:
 		btn = pointer.ButtonSecondary
 	case BTN_MIDDLE:
@@ -1073,19 +1081,17 @@ func (w *window) Perform(actions system.Action) {
 	// https://wayland.app/protocols/xdg-shell#xdg_toplevel:request:set_minimized
 	walkActions(actions, func(action system.Action) {
 		switch action {
-		case system.ActionMove:
-			w.move()
 		case system.ActionClose:
 			w.dead = true
 		}
 	})
 }
 
-func (w *window) move() {
-	if !w.inCompositor && w.seat != nil {
+func (w *window) move(serial C.uint32_t) {
+	s := w.seat
+	if !w.inCompositor && s != nil {
 		w.inCompositor = true
-		s := w.seat
-		C.xdg_toplevel_move(w.topLvl, s.seat, s.serial)
+		C.xdg_toplevel_move(w.topLvl, s.seat, serial)
 	}
 }