how to make pushbutton in fixed size inside layouted group box

[wagmare]

hi friends,
i am designed a group box inside four pushbuttons and i layout the group box .
actually i want to keep the pushbutton size (150 X 50) so inside i adjust the size but after i layout the group box it resized to default so please anybody help me to make the pushbutton constant size...
thank you

[jpn]

Set minimum and maximum size properties to the same value.

[wagmare]

thank you very much ... i made it...