Super simple patch that makes the auto reserve tank indicator on the HUD turn pink (or whatever color your full Etanks/explored map tiles are) when reserves are 100% full.

The best part is that it uses no freespace at all. See asm files for details on that, it's accomplished by optimizing parts of the HUD routine and deduping an auto reserve tilemap.

Works with xkas and asar. Credit to PJ's logs as always.

If you have any issues or need help repointing things due to patch conflicts, feel free to get a hold of me.

See also: My reserve tank bugfixes patch which makes reserves better.
https://metroidconstruction.com/resource.php?id=418

UPDATE February 15, 2023: Added a "Compatability Version" of the patch which rewrites less of the HUD routine at the cost of using some freespace (about 21h bytes that can be easily relocated anywhere from bank $80-$BF). Both versions work exactly the same on a vanilla ROM, the Compatability Version is designed to be more compatible with other patches which edit the HUD like Oi27's Instant Pickups.

NOTE: To stop the Compatability Version patch from drawing the top arrow on the auto reserve icon (to make it compatible with even more HUD stuff like the VARIA HUD), make the following changes:
- Comment out line 39 by putting a semicolon before the DW statement
- Comment out lines 56, 57, and 58
- On line 71, change STA $7EC618,x to STA $7EC658,x