Mdi child fit when resizing parent

Hello everyone!
I have a problem with mdi parent and child. I want when resizing, or maximize, or minimize parent, child to fit to the parent size and all the controls from it (at controls I"m refering at position). For example when you open a window of an application and when you change its size all the controls are fitting to the screen, not like size but like position.
I hope I made it clear, if not, please tell me.
Thanks in advance!


The main problem is the one with mdi parent and child: "I want when resizing, or maximize, or minimize parent, child to fit to the parent size".