how the stained glass windows in Bracia Jabłkowscy's Department Store
You mean the building that's mostly the Traffic bookshop.
Quite a few buildings round that part of the centre survived. By the time the German army got to dealing with that part of town, supplies of explosive materiel were beginning to run very low, and eventually they even stopped using petrol in order to conserve it for evacuations and retreat. Hence the number of Seccessionist buildings that survived in the southern part of the centre and the top end of Mokotów.