This patch will cause certain items to drop from the item box in a stunned state. By default, the key and all four Koopas drop stunned, while all other items drop normally.
This patch, however, does not fix the glitched graphics that occur when the item box contains something other than a mushroom, flower, feather, or star, nor does it include the list of item box values.
Tested with Asar v1.71, SNES9x v1.58, in both normal and SA-1 ROMs. Patch works as intended, even though items in item box look glitchy because SMW doesn't handle these. In other words, you need to use this patch to modify their tilemaps.