BoxLayout making component too big

Hello,

if i put some component in a FlowLayout, they have a "clever" size. But i need to have them verticaly, so i use a BoxLayout(Y_AXIS). But the layout make the components big to fill all the panel space (in fact the 2 radio button are ok, but the combo box has a big height).

How can i prevent that? I reaaly juste need a flowlayout but vertical. If i must say wich size (preferred, min, max) to use, it's simpler to use a "null" layout.

Thx for your help
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