Resizing child widget on changing size of parent?

hi,
i want to change the size of child widgets(QLineEdit...) on changing the size of parent
widget. How can i do it??
Can i do this thing by changing some parameters in property of child widget so that i dont hv to code it??
thnx

the easiest way is to set the childs into a layout., i think. Then the childs change their size when you resize the parent

thanx,bt dis is not workin........

i use qt designer -> right button on parent widget and "Lay out", that works...