The texture of the light grey stained glass pane id the same as the gui texture for the inventory and the creative menu.
Environment
Win 10 x64bit, Java 1.8.0_171 x64bit
MC-129441
The texture for the light grey stained glass pane is the same as the gui background.
Resolved
Duplicate
0
Oversight, not a bug. You're better off posting this in r/minecraftsuggestions.