Can I create multiline control or combobox for input value in variable of process. And if I can do it, how it must declare in processdefinition.xml.
You currently cannot do this in the definition. I've been busy with to many other things the last weeks but I'm currently available again to pick up some things. One of which is a more customizable ui. The default 'generated' webapp will not show this. But some ideas are on its way for that as well. (look at the pageflow in 3.1)