Bug 4240 Can't edit class path entry (1GKEPIF)
There is no way to edit an existing entry for a library on the Java Build Path project properties page (other than editing the .classpath file directly). NOTES: EG (9/22/2001 11:42:11 AM) this is particularly annoying for variables. we should have an Edit button when a variable is selected.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/NewVariableEntryDialog.java
private class VariableSelectionListener implements IDoubleClickListener, ISelectionChangedListener {
		public void doubleClick(DoubleClickEvent event) {
			doDoubleClick();
		}
		public void selectionChanged(SelectionChangedEvent event) {
			doSelectionChanged();
		}
	}
	
	private static class FileLabelProvider extends LabelProvider {