Changed wxPropertyCategory to use same cell rendering code as regular properties. This allows labels for category columns other than the first. Rendering code was heavily modified to allow 'merging' of cells when needed.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63012 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/propgrid/property.h

@@ -98,7 +98,11 @@ public:
                               DontUseCellBgCol
     };
 
-    virtual void Render( wxDC& dc,
+    /**
+        Returns @true if rendered something in the foreground (text or
+        bitmap.
+    */
+    virtual bool Render( wxDC& dc,
                          const wxRect& rect,
                          const wxPropertyGrid* propertyGrid,
                          wxPGProperty* property,
@@ -171,7 +175,7 @@ public:
 class WXDLLIMPEXP_PROPGRID wxPGDefaultRenderer : public wxPGCellRenderer
 {
 public:
-    virtual void Render( wxDC& dc,
+    virtual bool Render( wxDC& dc,
                          const wxRect& rect,
                          const wxPropertyGrid* propertyGrid,
                          wxPGProperty* property,
@@ -2484,6 +2488,7 @@ public:
     int GetTextExtent( const wxWindow* wnd, const wxFont& font ) const;
 
     virtual wxString ValueToString( wxVariant& value, int argFlags ) const;
+    virtual wxString GetValueAsString( int argFlags = 0 ) const;
 
 protected:
     void SetTextColIndex( unsigned int colInd )