OCIA.net checks out the Enermax Seahawk Case in their latest review. Below is a direct quote from the review:

The window is not cut exactly rectangular. It has small tabs that stick out of its edges that secure it by snapping into metal slots on the panel. This design causes the fit to not be 100% snug. I noticed when removing and attaching the panel that the window rattled a little bit, but I wasn't worried about it falling out or anything like that.