I was talking about the support to only load the 10 missing sprites. These 10 sprites are not the first 10 sprites of the 16 and 18 sprites versions of the action5.
The 1, 6, 8, 11, 12, 14, 15, 16 (, 17, 18) sprite. To have compatiblity with the 16 (and my new defined 18) sprites action 05-0D, can these places not be changed. These 10 sprites must allways fit with the original ones and will be only used if no newWater newGRF (17 and 18 if a 16 sprites newGRF) is loaded. If a standart newGRF loaded these sprites (how you suggested) will be replaced by the new one.
I extracted the 10 sprite action5 from you openttdw.grf and created a separate newgrf, [...]
That would be much easier, download the shore.pcx and shore.nfo from the FS link and edit the head of the nfo file voilà: a stand alone 10 sprites newWater newGRF
[...] that I loaded into TTDP. The behaviour of TTDP is to ignore the action5 as it specifies to few sprites. So it does not directly break compatibility. But I assume, if the TTDP people want to also implement the 10 sprites version, they will get into trouble.
Of course ignore TTDP it. IIRC they do it in the same manner how OTTD: if the sprite count is wrong, don't load. And if the TTDP devs want to include these ten sprites they can not break the order or they break the compatiblity with the standart newWater newGRFs. So they must find a way to include them on the 1, 6, ... position how I must do.
Of course if you define, that this 10 sprite version must not be used by newgrfs with the exception of openttdw/d.grf, then I guess everything is fine.
Why should ?
PS to a mod: since this isn't an artist search, more a development discussion: is it maybe better to move this thread to the development section ?