Use HelloModality:

From description in Javadoc we know, that WINDOW_modal should block its owners hierarchy.

Start hello application : We have a window with different options.

step 1: Owner "checked"; APPLICATION_MODAL; press "create dialog"
result: we have a child which is APP.

step 2 (in new window): Owner "unchecked"; NONE; press "create dialog"
result: we created a root of new hierarchy. (problem 1: Why APPLICATION_MODAL window don't block a new window? Should i file a bug on this behavior, or this is some undocumented case, so I should file a bug on javadoc?)

step 3 (in the last, new window which is NONE): Owner "Checked"; WINDOW_MODAL; press "create dialog"
result: we have two hierarchies, each of them has two elements: root which is none and child, which is APP in first case and WIN in the second case

step 4 (in the second window which is APP): close this one (i mean close APP, created on step 1).
problem: root of second hierarchy became available, but it has i child which is WINDOW and that WINDOW should block this one root)