there is a bug when using openLookup with the following method signature:
public AbstractLookup openLookup(Class<? extends Entity> entityClass, Handler handler, OpenType openType)
When giving it an entity that only has a browse screen but no explicit “.lookup” screen, it would not open the lookup window saying: “No such screen - Screen ‘cpolwl$Customer.lookup’ is not defined”.
Attached you’ll find an example app. The openLookup call is in the mainWindow.