remove: - Hack used to close the combo box when mouse is clicked on it....

remove: - Hack used to close the combo box when mouse is clicked on it. Actually it should close automatically (otherwise it is not a combo box!). This is done by just trying to understand how selection works and how selection is propagated in GXT.
- Generally the flag 'allowEmpty' as it is not really used. Instead use properly 'setEmptyText' combined with 'applyEmptyText'.
add: - Some assertions when '*SelectionWidget.tryGetSelected*' is used.

SVN: 9222