Relates to: MC-176095 MC-199660 MC-208679 MC-250985
May also relate to: MC-159560
The bug
Much like the unused buttons mentioned in MC-268376, the anvil's texture contains a massive red rectangle which is always fully obscured by the text field. Deleting this rectangle from the texture file would indicate better that it is an unused feature which is never visible, and doing so would also knock down the file size.
How to fix
Remove these pixels from the texture file. I have two fixed versions of this texture attached - one for the default textures and another for Programmer Art. Fixing this should be as easy as replacing the textures with the versions attached.
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Can confirm, though it may make sense to instead fill in the background with either the gray color to match the background, or an empty version of the text box instead of leaving a gap in the texture, like so:
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