Laying out the components
how is the syntax for laying out the different visual components?
I think the most difficult part of creating a new form or other kind of window content is to place the elements so the form looks nice and ergonomic.
What kind of constructs did you include in your markup language to support the 'designer' of forms. (GridBagLayout is very powerful to layout almost any design but the 'normal' designer does not understand it at all, same is for nesting layouts).