size comboboxes

hello, i have 3 combobox and 3 horizontal spacer put in this way on my window

spacer1 - combobox1 --> vertical layout
spacer2 - combobox2 --> vertical layout
spacer3 - combobox3 --> vertical layout

all them are into grid layout.
I'd like that the width for all the combobox is equals at the widthest combobox size.
for example, if the combobox1 value is "123456789", the combobox2 value is "12345" and the combobox3 value is "12" the comboboxes size should be the combobox1 size value. Is it possible?
Thank

Yes, ignore the spacers, put all comboboxes into a single vertical layout and set the horizontal size policy of each combobox to minimum. See the attachment for an example.

thanks so much for your help!;)