Implemented RepaintAll() on Windows.

area_windows.go

@@ -698,6 +698,9 @@ func areaWndProc(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam _LPARAM) _LRESU
 		adjustAreaScrollbars(s)
 		repaintArea(s)					// this calls for an update
 		return 0
+	case msgRepaintAll:
+		repaintArea(s)
+		return 0
 	default:
 		return defWindowProc(hwnd, uMsg, wParam, lParam)
 	}

sysdata_windows.go

@@ -669,3 +669,19 @@ func (s *sysData) setAreaSize(width int, height int) {
 	}
 	<-ret
 }
+
+func (s *sysData) repaintAll() {
+	ret := make(chan uiret)
+	defer close(ret)
+	uitask <- &uimsg{
+		call:		_sendMessage,
+		p:		[]uintptr{
+			uintptr(s.hwnd),
+			uintptr(msgRepaintAll),
+			uintptr(0),
+			uintptr(0),
+		},
+		ret:		ret,
+	}
+	<-ret
+}

uitask_windows.go

@@ -39,6 +39,7 @@ const (
 	msgRequested = _WM_APP + iota + 1		// + 1 just to be safe
 	msgQuit
 	msgSetAreaSize
+	msgRepaintAll
 )
 
 var (