Switching between MDI child windows...

I have an MDI application that is causing slight problems when I try to
programmatically switch between child forms. When I press CTRL+TAB, the
forms switch without much of a flicker at all. But when I try to fire
an MDI switch from a toolbar button, I get a pretty noticeable flicker.

The way I am changing forms is through the use of the Activate() method
on the child form. For instance,

nextChild.Activate();

I've tried using the ActivateMdiChild method, i.e.,

this.ActivateMdiChild(nextChild);

but it doesn't seem to do anything.

Is there something that I'm missing? I really just want to know how the
framework Form class handles a CTRL+TAB key press so I can do the same
thing.

Thanks,
Rich