Hide tooltip when its associated window is hidden in wxMSW.

Don't leave the tooltip shown on screen if the window it was shown for was
hidden or iconized (without moving the mouse, as that would have dismissed the
tooltip as well).

Closes #16265.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76657 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/tooltip.h

@@ -69,6 +69,10 @@ public:
     // makes sense to use it for tooltips associated with a single window only.
     void SetRect(const wxRect& rc);
 
+    // Called when TLW shown state is changed and hides the tooltip itself if
+    // the window it's associated with is hidden.
+    static void UpdateVisibility();
+
 private:
     // Adds a window other than our main m_window to this tooltip.
     void DoAddHWND(WXHWND hWnd);