wxGridCellAttr::Clone() added to allow the demo of custom grid cell attr provider to work

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@6339 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/newgrid/griddemo.h

@@ -158,6 +158,22 @@ private:
     BigGridTable* m_table;
 };
 
+// ----------------------------------------------------------------------------
+// an example of custom attr provider: this one makes all odd rows appear grey
+// ----------------------------------------------------------------------------
+
+class MyGridCellAttrProvider : public wxGridCellAttrProvider
+{
+public:
+    MyGridCellAttrProvider();
+    virtual ~MyGridCellAttrProvider();
+
+    virtual wxGridCellAttr *GetAttr(int row, int col) const;
+
+private:
+    wxGridCellAttr *m_attrForOddRows;
+};
+
 // ----------------------------------------------------------------------------
 // another, more realistic, grid example: shows typed columns and more
 // ----------------------------------------------------------------------------