Activating child form via right mouse click

Question

I created an mdi form, and then added three children to it.
When I click on any child form it becomes the active one and its title becomes bluish to indicate that.
The issue that I have is that when I click on any child form via right mouse click, I am not able to get that form to be the active or the selected form. How can I activate a child form via right mouse click only?

Thanks.