Interesting question. Unknown. Generally, many airlines fly their 737 variants with one or two rows which has missing window but not all have missing window. Looking at seatguru map, 739 Version 1 (without Premium Main Cabin Seat) has missing window seats in row 10 and 12. However, map for 739 Version 2 (which has Premium Main Cabin Seat), do not indicate a missing window. Every picture I've seen of AS 737-900 seem to indicate, there should be two regions which should be missing a window.... As reconfiguration process doesn't create new window space, I'm thinking it has created partial window than missing window for some of these previously identified rows.

Jiburi