Clients may contribute the {@link org.eclipse.gmf.runtime.emf.ui.preferences.PathmapsPreferencePage}
for their application preferences using the org.eclipse.ui.preferencePages
extension point.
The {@link org.eclipse.gmf.runtime.emf.ui.preferences.PathmapsPreferencePage} allows the user to
specify the path variables that should be considered for modeling. Path variable are created on
the "Linked Resources" preference page, and selected for modeling using this page.