Here is a HoverBorderLayout I made. It is compatible with GXT 2.2.4. It expands the popup of a collapsed panel on mouse over and collapses it on mouse out. You can set the width of the collapsed section (standard is 24, min is 2).

Here is the code:

HoverBorderLayout.zip

Let me know if you have questions or improvements.

Regards,
Carl Pritchett