How to add select box as grid columns on property page

Hi,

I am writing my own plugin and I want to have a grid on property page. I want to specify a select box as grid column and also want to populate its data using a ajax url. If I specify my own options hard codded then it is working but when I specify options_ajax then it renders a text box

Please suggest how can I render a select box as a grid column which populates its value from a ajax url.

Also wants to change the value of second column selectbox depending on first column select box selection

Thanks,

promod