The front panel assembly is the final piece to the puzzle.

Unfortunately, the display and front glass are fused, with a layer of optical adhesive. The glass is then adhered to the plastic display frame, making a single assembly. Not a big surprise.

Getting a look at the second liquid damage indicator on the back of the screen, and—whoa, what's this hiding down there?

Looks like we've spotted the touchscreen controller, a Synaptics S5000B.

This chip is responsible for the S4's super-sensitive touchscreen, which even works with gloves.