What happens at runtime – PB Docs 2018

Data stored in a DataWindow object is stored within the actual
object itself, so when a window opens showing such a DataWindow, the
data is already there. There is no need to issue Retrieve to get the
data.

PowerBuilder never retrieves data into a drop-down DataWindow
that already contains data. For all other DataWindow objects, if you
retrieve data into a DataWindow object stored with data, PowerBuilder
handles it the same as a DataWindow object that is not stored with
data: PowerBuilder gets the latest data by retrieving rows from the
database.