void setProperty() throws ScriptException {
		// what possible good is this?
		// set property foo bar is identical to
		// set foo bar

		checkLength4();
		if (statement[2].tok != Token.identifier)
			propertyNameExpected();
		String propertyName = (String) statement[2].value;
		switch (statement[3].tok) {
		case Token.on:
			viewer.setBooleanProperty(propertyName, true);
			break;
		case Token.off:
			viewer.setBooleanProperty(propertyName, false);
			break;
		case Token.integer:
			viewer.setIntProperty(propertyName, statement[3].intValue);
			break;
		case Token.decimal:
			viewer.setFloatProperty(propertyName, floatParameter(3));
			break;
		case Token.string:
			viewer.setStringProperty(propertyName, stringParameter(3));
			break;
		default:
			unrecognizedSetParameter();
		}
	}