Mouse sprite and ram aren't linked

^{Originally posted [here]( https://github.com/nesbox/TIC-80/discussions/2577) until i just remembered issues exist. sorry.

I found out a weird bug with the sprite the mouse uses
rather than always use the data in ram, the mouse seems to only use the sprite in ram during startup, after which it can't be changed (not linked between each other)

here's some lua code to explain what I mean
**(you'll need to put a sprite in spr 257):**

```
--mouse sprite "bug"
--put something in sprite 257 for this
--preferably something that isnt just 1 color
t=0
function TIC()
cls()
mx,my=mouse()
--self explanatory
print("sprite 257:",mx-64,my-10,12)
--self explanatory
print("mouse:",mx-64,my,12)
--draws sprite 257 8 pixels under mouse
spr(257,mx,my-10)
--should set mouse sprite to 257
poke(0x3ffb,1)
-- writes a semi checkboard of
-- white and red to sprite 257
-- after 5 seconds
if t>300 then
memset(0x6020,0xc2,32)
end
t=t+1
end
```}

nesbox / TIC-80

Mouse sprite and ram aren't linked #2583