I would like to be able to blacklist some Mod GUI's, like the Library GUI from Enchiridion, as the slots overlap that GUI.

A screenshot is attached.

Version: 2.1-legacy 1.10.2

I was thinking about something like that, your blacklist idea would be a good way.

At first I could blacklist the whole mod, removing just certain GUIs would be more tricky.

Or perhaps add a way for it to detect the edge of gui's, similar to how JEI does it, if that's possible.
I found out the it also overlaps the tinker's gui in the crafting station when a chest is next to it. And if the armor slots are switched to the left side, it overlaps JEI's grid.

The problem is I need to detect the gui size twice, once on the client to draw the background and once on the server to position the slots.

On the screenshot, the slots are on the right position (aligned with the hotbar), but the background on the wrong place. That shouldn't happen because the background is the easy one...

I'll have to see how JEI detects the gui area.

Ok, and which ever works is fine with me.