public MyDialog(Shell parentShell) {
super(parentShell);
setShellStyle(SWT.CLOSE | SWT.MODELESS | SWT.BORDER | SWT.TITLE);
setBlockOnOpen(false);
}

http://www.eclispezone.com/eclipse/forums/m92149780.html

An example of creating non-modal dialog boxes which extend the Dialog class is SWT/Eclipse

create modeless JFace dialog ...

plugin

Java