When hovering your mouse over an item, the item specify box will clip underneath the item amount of other items in your inventory. (For example, if I were to hover my mouse over "redstone", the box that specifies that the item is redstone would clip underneath the item amount of something else in my inventory.) Not a game breaking glitch in any way, shape, or form, but something that should definitely be addressed, as it looks very unpolished and could annoy other players.

All you have to do is click whatever button you use to access your inventory, hover over an item, and the bug will arise.