Listen to Messages of child control

Hi all,

I'm wanting to listen for a specific message sent to a child control of the one I'm working with. Case in point, I have a NumericUpDown and I want to listen to the messages received by it's internal TextBox, so that when I find the one I want (WM_CONTEXT see note*) I can do some processing.

Any thoughts? I've tried checking for changes to the ContextMenu and / or ContextMenuStrip, but neither ever get altered, presumably because its the windows system menu I'm actually looking for.

* WM_CONTEXT pops up the windows system menu for standard controls if it wasn't previously intercepted. There is no corresponding message for when this menu is closed.