How can I correctly align widgets on Glade?

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http://askubuntu.com – I have to make three combo boxes become aligned with each other, on the right of my application, which will contain pre-defined responses to questions asked with labels on the left. However, I can not imagine a way to do this with Glade, since it insists on placing all the widgets next to each other. How can I properly align these widgets? (HowTos)