This is a variation of the simpler glass backdrop. Like regular glass backdrops, fancy glass backdrop blocks have transparent back tiles, but when placed contiguously with other fancy glass backdrops, these blocks display thin dividers between panes, with the outer edges of the whole showing a thin wooden border.
How to Obtain
This backdrop can be crafted, and is also found in various world-generated structures, where it can be mined. This backdrop is also included in the building pack, which can be purchased via the "Shop" tab.
This is an excellent backdrop to create tall Victorian windows. Place six or more in a tall rectangle to see the beautiful dividers.