Add support for showing "elevation" icon in wxMSW buttons.

Add, document and test in the widgets sample wxButton::SetAuthNeeded().

Closes #11705.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63421 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/button.h

@@ -80,6 +80,8 @@ protected:
     // usually overridden base class virtuals
     virtual wxSize DoGetBestSize() const;
 
+    virtual bool DoGetAuthNeeded() const;
+    virtual void DoSetAuthNeeded(bool show);
     virtual wxBitmap DoGetBitmap(State which) const;
     virtual void DoSetBitmap(const wxBitmap& bitmap, State which);
     virtual wxSize DoGetBitmapMargins() const;
@@ -88,6 +90,9 @@ protected:
 
     class wxButtonImageData *m_imageData;
 
+    // true if the UAC symbol is shown
+    bool m_authNeeded;
+
 private:
     DECLARE_DYNAMIC_CLASS_NO_COPY(wxButton)
 };