If you place iron bars in a line along the y axis, all bars going that way have a graphical glitch when touching blocks (not when touching other bars, though.)
I couldn't really get a picture of it because the graphical glitch is a flashing look.
Related issues
duplicates
Comments

Duplicate of MC-220, please use the search function to see if your bug has already been submitted. Currently over 53% of tickets are being closed as duplicate.