txtValueLayoutData = new GridData(GridData.FILL_BOTH);
txtValueLayoutData.minimumHeight = 200;
txtValue.setLayoutData(txtValueLayoutData);
WGEventScriptMetaFieldDefinitionModel eventScriptMetaFieldDefinitionModel = new WGEventScriptMetaFieldDefinitionModel(_model);
eventScriptMetaFieldDefinitionModel.addListener(new BeanChangedListener<WGMetaFieldDefinition>() {
public void changed(WGMetaFieldDefinition bean) {
_treeViewer.refresh(bean, true);
_model.fireModelChanged();
}
});