Redraw / Refresh / Clean up controls

Hi, I'm working on a Pocket PC application in C#. I have a listbox and on "SelectedIndexChanged" a lot of things are set in motion (loading data and so on...) Problem is that the listbox wont collaps untill the process described above is finished. This looks very unprofessional. Does some one knows how I can refresh or redraw the listbox control so that it collaps first and then the underlying process is started. I know its eyecandy but's important ! Thank you ! Kind regards, ShAdOwHuNtEr