Continue the implementation of trigger rules (ex scene rules)

pkg/windowmanagerhandler/window_manager_handler.go

@@ -0,0 +1,27 @@
+package windowmanagerhandler
+
+import (
+	"context"
+	"fmt"
+)
+
+type WindowManagerHandler struct {
+	*PlatformSpecificWindowManagerHandler
+}
+
+func New() (*WindowManagerHandler, error) {
+	wmh := &WindowManagerHandler{}
+	if err := wmh.init(); err != nil {
+		return nil, fmt.Errorf("unable to initialize a window manager handler: %w", err)
+	}
+	return wmh, nil
+}
+
+func (wmh *WindowManagerHandler) WindowFocusChangeChan(ctx context.Context) <-chan WindowFocusChange {
+	return wmh.PlatformSpecificWindowManagerHandler.WindowFocusChangeChan(ctx)
+}
+
+type WindowFocusChange struct {
+	WindowID    WindowID
+	WindowTitle string
+}