Add impl for IsFrozen

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42084 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/mac/carbon/window.h

@@ -65,6 +65,7 @@ public:
                           const wxRect *rect = NULL );
     virtual void Freeze();
     virtual void Thaw();
+    virtual bool IsFrozen() const;
     
     virtual void Update() ;
     virtual void ClearBackground();

src/mac/carbon/window.cpp

@@ -2301,6 +2301,11 @@ void wxWindowMac::Thaw()
 #endif
 }
 
+bool wxWindowMac::IsFrozen() const
+{
+    return m_frozenness != 0;
+}
+
 wxWindowMac *wxGetActiveWindow()
 {
     // actually this is a windows-only concept