Add test for context menu, fixed mem leak, fixed focus problem when re-editing same item

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@53126 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dataview.cpp

@@ -975,8 +975,14 @@ static GtkCellEditable *gtk_wx_cell_renderer_start_editing(
 {
     GtkWxCellRenderer *wxrenderer = (GtkWxCellRenderer *) renderer;
     wxDataViewCustomRenderer *cell = wxrenderer->cell;
+    
+    // Renderer doesn't support in-place editing
     if (!cell->HasEditorCtrl())
         return NULL;
+        
+    // An in-place editing control is still around
+    if (cell->GetEditorCtrl())
+        return NULL;
 
     GdkRectangle rect;
     gtk_wx_cell_renderer_get_size (renderer, widget, cell_area,