The common dialog classes in SWT descend from SWT's abstract Dialog class (org.eclipse.swt.widgets.Dialog).
A dialog's parent, which is passed to the constructor, is always a Shell object.
ConstantDescription
SWT.APPLICATION_MODALModal to the application; input is blocked to other windows in the application.
SWT.PRIMARY_MODALModal to the parent window of the dialog; input is blocked to the parent of the dialog only.
SWT.SYSTEM_MODALInput is blocked to all other windows of all applications until the dialog is dismissed.
SWT.NONEModeless (the default).