In order to open a modal dialog, you need to pass a parent window, and pass the necessary flags for the dialog to be modal of course.
Depending on where you are in the e
Not quite exactly what you want to do but you may need to use SWT.APPLICATION_MODAL, SWT.DIALOG_TRIM etc. when creating your dialog in order to make it a modal dialog (but perhaps that's not what your question was about).
See this link for more info.