Thanks to Alcaro, I managed to apply the patch, but now there is this problem. Whenever I try enabling Sprite Nessage Box in a level with layer 3, it doesn't work. Instead, it still displays the message on layer 3.
No, applying both patches won't mean they work together and magically create an expanded sprite message box. These two patches drastically change the message box system in their very own ways, that's all.
Yes. You can't display more than 32 OAM slots, or 34 8x8 tiles (whichever is lower), on the same scanline.
I don't know if the limits are hit; it's not impossible if you put a box at the start of level 106, and maybe in some of the Wiggler levels, but shouldn't exist outside of that.
However, it can be made impossible (unless you're specifically trying to hit this limit) by ensuring the patch doesn't add OAM tiles for spaces, and that the patch disables OAM tiles that are covered by the message box, both of which should be reasonably easy to implement.
-------------------- <blm> zsnes users are the flatearthers of emulation
I found a bug with this patch. Apparently, if I apply this patch on a SMW game that has any patch that messes with the windowing effects of the game applied to it, then the message box will show behind the layer 1 FG and random scanlines appear all over the level, while the message is on.