I'm coming back with a new question :).
There is a way to minimize a radform just with the titlebar and keep the windows active ?
I found the TitleBar_Minimize event handler but I don't know which options use.
step1.png the windows is active
step2.png I click on the minimize button in title bar
step3.png I have my radform active and reducted (without resizebutton), I can click on the maximum button to show the radform content.