diff --git a/stdwndclass_windows.go b/stdwndclass_windows.go
index 035751c..38031e7 100644
--- a/stdwndclass_windows.go
+++ b/stdwndclass_windows.go
@@ -45,8 +45,8 @@ func stdWndProc(s *sysData) func(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam
 			// TODO
 			return 0
 		case _WM_CLOSE:
-			if sysData.closing != nil {
-				sysData.closing <- struct{}{}
+			if s.event != nil {
+				s.event <- struct{}{}
 			}
 			return 0
 		default:
diff --git a/sysdata.go b/sysdata.go
index 339d73e..c15e922 100644
--- a/sysdata.go
+++ b/sysdata.go
@@ -8,15 +8,9 @@ import (
 // The sysData type contains all system data. It provides the system-specific underlying implementation. It is guaranteed to have the following by embedding:
 type cSysData struct {
 	ctype			int
-	parentWindow		*sysData
-
-	// for Window
-	closing	chan struct{}
-
-	// for Button
-	clicked	chan struct{}
+	event			chan struct{}
 }
-func (c *cSysData) make(initText string, initWidth int, initHeight int) error {
+func (c *cSysData) make(initText string, initWidth int, initHeight int, window *sysData) error {
 	panic(runtime.GOOS + " sysData does not define make()")
 }
 func (c *cSysData) show() error {