Maximizing form that have constrain set to false

I have a border layout viewport.

In viewport I have a toolbar which is region north and a panel which has region parameter set to center and layout absolute.

In the panel I have a window which is maximizable. When I set constrain to true to that window, and maximize it, everything works OK, but when I set constrain to true I have two problems:

1. how to set constrain only to south, east and west - for I don't want user to move form over the toolbar

2. when I click on maximize button, I want form to be maximized as it is when constrain is set to false. Again, I don't want window to be positioned over the toolbar.

Here is described example:

http://ift.tt/QksN1j

Thanks for answering.