I don’t understand how what you wrote helps me.
Can you explain, please?

But, first let me try to explain my problem again. (Hopefully, more clearly …)
Let’s say I have 3 UserControls on my form: MyUserCtrl, UserCtrl2, & UserCtrl3. All of them contain buttons, text-boxes, etc.
When MyUserCtrl is in focus, I would like pressing ‘Enter’ to fire the ‘Click’ event of a specific button on this UserControl.
If MyUserCtrl is not in focus, pressing ‘Enter’ should not do so.

How can I achieve that?