Run attached code;

Click init button to create initial stage with none modality and without parents.

in stage0 click button NONE. it will create child stage with none modality and with stage0 as parent.
in stage1 check checkBox "Wait after show modal window" and click button NONE. It will create stage2, which has stage1 as parent, and stage1 waits for stage2 closing.

Close stage1.
On windows: stage1 and stage2 will be closed.
On linux: stage1 will be closed, stage2 will continue existing.