diff --git a/rfb_win32/ToolBar.h b/rfb_win32/ToolBar.h
index feed1a0..2242c2a 100644
--- a/rfb_win32/ToolBar.h
+++ b/rfb_win32/ToolBar.h
@@ -118,6 +118,9 @@
       // hide() hides the toolbar window.
       void hide();
 
+      // isVisible() check the toolbar window on visible.
+      bool isVisible();
+
     protected:
       HWND hwndToolBar;
       HWND parentHwnd;