I want to see my modal panel when I click on the button. The problem is that when I click on that button, the modal panel is dispalayed, and when the page is rerendered (the whole page as I don't use Ajax here), the combobox has an empty value. Indeed, the bean receives, from the request, a null value for the bean property choice.
If I use a <a4j:commandButton .../> instead of the <h:commandButton .../>, then the behavior is correct (i.e. I get the correct value for choice on my bean).
However, for some reason, I don't want to use an A4J CommandButton here, just a "basic" one.