TOOLKIT_EXCLUDE indicates that a top-level window
won't be blocked by application-modal or toolkit-modal dialogs. Also,
it isn't blocked by document-modal dialogs from outside of its
child hierarchy.
The "toolkitModality"
AWTPermission must be granted
for this exclusion. If an exclusion property is being changed to
TOOLKIT_EXCLUDE and this permission is not granted, a
SecurityEcxeption will be thrown, and the exclusion
property will be left unchanged.