Bukkit

What steps will reproduce the problem?
1.  Trying to open a chest/furnace with thin_glass on top of it (or where the chest can be accessed but the block is occupying the space where you look through).

What is the expected output? What do you see instead?
The chest should open without hindrance, but instead gives the warning that the chest is being accessed through a block.

What version of the product are you using?

Chestfix 0.5

Do you have an error log of what happened?
[CHESTFIX] You used a CHEST but were looking at THIN_GLASS

Please provide any additional information below.

Also tried using iron_bars, fences, vines, fence_gates, nether fence, and trapdoors. Only Glass Panes seem to be the issue.

Currently I'm unsure about how I'd go to fixing this, but I know exactly what you're talking about.

If it's a serious issue, try add glass panes to the config of transparent blocks, but that means players will be able to freecam through glass.

I'll keep thinking on ways to fix it though.