ComboGrid Problem: How to get ComboBoxEvents before the DataGrid

[STW]

I made a ComboDataGrid (ParentControl). When the ComboBox (ChildControl) in the DataGrid has the Focus then I want to catch any Key Events from the ComboBox. The ComboGrid should react as follows: When the focused cell is not the ComboBoxColumn then the DataGrid should act normal, what means when the user presses Up or Down Arrows, the Focused Row chould change. When the focused cell is in a ComboBoxColumn then it should be possible to press Ctrl+Up or Down Arrow to scroll up and down in the ComboBox. To solve this I need any keyEvent of the ComboBox before the DataGrid. I tried with ProcessCmdKey(), ProcessKeyEventsArgs() but could not get what I wanted. Big Thanks for all who will reply. Stefan