fEditButton.setEnabled(substitution.hasChanged() && (substitution.fState == NLSSubstitution.EXTERNALIZED));
fEditButton.setEnabled(substitution.getState() == NLSSubstitution.EXTERNALIZED);
    private void updateButtonStates(IStructuredSelection selection){	    fExternalizeButton.setEnabled(true);	    fIgnoreButton.setEnabled(true);	    fInternalizeButton.setEnabled(true);	    fRevertButton.setEnabled(true);	    	    if (containsOnlyElementsOfSameState(NLSSubstitution.EXTERNALIZED, selection)) {	        fExternalizeButton.setEnabled(false);	    }	    	    if (containsOnlyElementsOfSameState(NLSSubstitution.IGNORED, selection)) {	        fIgnoreButton.setEnabled(false);	    }	    	    if (containsOnlyElementsOfSameState(NLSSubstitution.INTERNALIZED, selection)) {	        fInternalizeButton.setEnabled(false);	    }	    	    if (!containsElementsWithChange(selection)) {	        fRevertButton.setEnabled(false);	    }	    	    if (selection.size() == 1){	        NLSSubstitution substitution= (NLSSubstitution) selection.getFirstElement();		        fEditButton.setEnabled(substitution.hasChanged() && (substitution.fState == NLSSubstitution.EXTERNALIZED));	        	    } else {		        fEditButton.setEnabled(false);				    }	}