This patch reduces the width of the "static camera region" (the range where the screen doesn't scroll left or right by the player) to a single pixel, removes the auto "look ahead" feature in smw and makes the screen always centered with the player (ignoring L/R scrolling, but still has the reduced "static camera region").
Update: Added a newer version (with the old version in case you want it) that makes the screen tightly follow Mario vertically (the vertical scroll area is also reduced to a single line) when you set the vertical scroll to "vertical scroll at will". This is more ASM-flexible. See readme for details. And also allow the bottom 16x16 row to be seen (both).
Another update: Also include a non-instant-scroll to prevent player-warp glitches.
v3.2 update: Fixed a crash on vertical levels due to a hijack at $00F77B.
v3.3 fixed a missing SA-1 [|!addr] at line 324, which caused the screen shaking issue (or snapping scroll on Bsnes+) on SA-1 vertical levels when using the non-instant scroll.