Don't Hide My Items
A mod that fixes the bundle UI in 1.21.2+
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Don't Hide My Items
Don't Hide My Items!

This is a simple, client-side mod that fixes the bundle UI in many ways: 1. Removes all the weird padding between items 2. Makes all the items in the bundle show, always 3. Makes the bundle fill from the top left like... every other container (instead of the bottom right in vanilla) 4. Adds a number showing how full the bundle is, as well as the bar 5. Adds four more columns (for a total of eight), now that there's room for more without the padding.
For context, here's what the vanilla bundle UI looks like: (ew)

Please note that this was a mod made in an evening with not very much focus on compatibility. Other mods that modify bundle rendering will likely conflict.