Override Do{Freeze,Thaw}() instead of {Freeze,Thaw}() in wxPropGrid code.

{Freeze,Thaw}() themselves are not virtual any more, so overriding them
doesn't really work and it is unnecessary to reimplement the reference
counting already done by the base class anyhow, so override the DoXXX()
versions instead.

Closes #15877.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/propgrid/manager.h

@@ -483,12 +483,6 @@ public:
     */
     bool IsAnyModified() const;
 
-    /**
-        Returns true if updating is frozen (ie Freeze() called but not yet
-        Thaw() ).
-     */
-    bool IsFrozen() const { return m_pPropGrid->m_frozen > 0; }
-
     /**
         Returns true if any property on given page has been modified by the
         user.
@@ -635,9 +629,6 @@ public:
     //
 
     void SetId( wxWindowID winid );
-
-    virtual void Freeze();
-    virtual void Thaw();
     virtual void SetExtraStyle ( long exStyle );
     virtual bool SetFont ( const wxFont& font );
     virtual void SetWindowStyleFlag ( long style );
@@ -646,6 +637,9 @@ public:
 protected:
     virtual wxSize DoGetBestSize() const;
 
+    virtual void DoFreeze();
+    virtual void DoThaw();
+
     //
     // Event handlers
     //