Bug 5449 TVT Text Expansion/Truncations in new java class dialog
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/VariableBlock.java
public void customButtonPressed(DialogField field, int index) {
			switch (index) {
			case 0: 
				editEntries(null);
				break;
			case 1: 
				List selected= fVariablesList.getSelectedElements();			
				editEntries((CPVariableElement)selected.get(0));
				break;
			}
		}