Disable Maximize, Minimize and [X] box in MDI Child form

Question

Hi

I have create an application with a MDI form.
All the MDI child forms would be maximized.
I cannot disable the maximize, minimize and [X] box of the child forms at top right corner even I had setted the child forms' maximizeBox = false, minimizeBox = false and FormBorderStyle = none.

Is it possible to disable it?!

Thx so much~