Tab navigation not working properly on IE9 (or IE10) when using a combobox inside a grid

I have a couple of grids that are keyboard navigatable and have combobox custom editors. Keyboard navigation works fine while moving between cells and hitting enter to select a cell to edit and even hitting enter to select an item on the combobox after navigating with the keyboard works fine.

Hoewever, if you use your keyboard to select an option from the combobox and then hit tab, the selected option is not preserved, basically Tab acts the same as the Esc key on IE9 and IE10. This does not happen in either Chrome or Firefox, but unfortunately our corporate users are all using IE9 so they are getting very annoyed by this since it seems like a natural thing to do when using keyboard input.

Here's an modified example taken from your demos where you can see this behavior.

http://jsbin.com/agowir/2/

Thank you