Changed storeSysData() on Windows to write the HWND to the sysData structure there. This will be important for removing some of the TODOs from areaWndProc().

stdwndclass_windows.go

@@ -60,7 +60,9 @@ func storeSysData(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRES
 		cs := (*uintptr)(unsafe.Pointer(lParam))
 		saddr := *cs
 		setWindowLongPtr(hwnd, negConst(_GWLP_USERDATA), saddr)
-		// don't set s; we return here
+		// also set s.hwnd here so it can be used by other window messages right away
+		s := (*sysData)(unsafe.Pointer(saddr))
+		s.hwnd = hwnd
 	}
 	// TODO is this correct for WM_NCCREATE? I think the above link does it but I'm not entirely sure...
 	return defWindowProc(hwnd, uMsg, wParam, lParam)

sysdata_windows.go

@@ -179,7 +179,12 @@ func (s *sysData) make(window *sysData) (err error) {
 		}
 		return fmt.Errorf("error actually creating window/control: %v", r.err)
 	}
+	if !ct.storeSysData {				// regular control; store s.hwnd ourselves
 		s.hwnd = _HWND(r.ret)
+	} else if s.hwnd != _HWND(r.ret) {	// we store sysData in storeSysData(); sanity check
+		// TODO really panic?
+		panic(fmt.Errorf("hwnd mismatch creating window/control: storeSysData() stored 0x%X but CreateWindowEx() returned 0x%X", s.hwnd, ret))
+	}
 	if !ct.doNotLoadFont {
 		uitask <- &uimsg{
 			call:		_sendMessage,