Use the keys Alt+Ctrl+Shift+W with VoiceOver running on a Mac to get it to read out the current dialog.

When reading out a dialog with a TabPane in, the following issues are noted:

- VO selects each tab in turn and reads out the tab name, and as each tab is selected, the tab is switched to.
- Reads out the Close button of a tab even if it doesn't have one
- Once all the tabs are read out, the contents of the tab pages are read out - starting with the first tab which is no longer selected.

VoiceOver should read each of the tabs without selecting them, then read only the content of the selected tab.

See also:
Issue JDK-8151974 - Invisible controls are still accessible by screen readers.
Issue JDK-8151989 - Content of unselected tabs of a TabPane is accessible to screen readers.