Pathy,
Well the VE Project’s integration and nightly builds have a working SWT editor in them, you will need to install them against certain versions of Eclipse (the ve site can give you more detail: http://www.eclipse.org/projects/vep IIRC)
Also the SWT-Designer product, while commercial, has extremely high acclaim for being an excellent GUI builder. You might consider checking it out if the VEP project doesn’t provide what you need yet.