Wheel action when mouse button down (ie mbtn_right+wheel_up add volume +5)

I tried a bit as I saw there's KEYDOWN flags but my knowledge is pretty limited and I think I'm wasting too much time for what might be a two-liner or something, maybe.

Expected behavior of the wanted feature

Well as the titles says, include mouse buttons on key down events. Right mouse button down + wheel up = volume up

Alternative behavior of the wanted feature

None I guess.

Log file

mpv_output.txt

On kind of a side-note, if anyone could let me know the proper way of adding extension specific keybinds it would be awesome. I suppose it's something I'm doing wrong but no idea what since one the examples below works, the other not.

Doing this in mpv.conf or example works as expected, as in will disable osc only in jpg files.
[extension.jpg]
osc=no

Doing this in input.conf however seems to override the default binds as if I did not use any profile at all so the bind is used in all file extensions.
[extension.jpg]
WHEEL_UP playlist-next

(that's not an actual bind I'm planning to use, hence the 'feature request')

edit: I can also not get include=C:\Users\user\AppData\Roaming\mpv\image-input.conf in mpv.conf to work under any circumstance? No idea what's up there either. Sorry for off-topic but it's all under the same issue and I've basically no idea where I'm at fault and where the program.
My goal as you probably guessed is to have mpv for both video and image playback as I find it to do an awesome job at that. Load a file in a folder with autoload, then play anything, with style! hah ;) Just need those binds.. I discovered mpv when I used linux a bit, now I use it on windows too in place of mpc-hc and irfanview. So yeah, good job! 👍

Start by tracing the KEYDOWN handling and the input.conf profile behavior described in the issue, then compare it with the working extension profile in mpv.conf. Check how WHEEL_UP bindings are parsed when a mouse button is held. Done means mouse-button-plus-wheel bindings and extension-specific input profiles behave as requested.