Sorry it was not very clear, read a foreign language is one thing, writing is another
To sum up, when i tested the code Zaela_S shared, it was what I was looking for ( a way to make spells available to other classes at the appropriate level )
But once in game I had a couple issues like 'you missed a note' as fizzle message when casting spells instead of 'your spell fizzles' ( I thing i read somewhere bard songs could cause that bug ), as well as pet's focus effects not working anymore, so i removed all non caster classes from Zaela's code.
Then it was perfect.
When it came time to change scrolls in game to be writable by all classes, I just put 65535 in the item table for spell scrolls. It worked but you could see all the classes in the description of the scroll with those who cant use it, like war(255),rog(255) etc..
For cosmetic purposes I went with that (bruteforce) method to add the class bitmask, 4096 for mage for example, excluding the spells mages already known and also excluding the spells mages shared with other classes ( like invisibility ) because when I added the bitmask the way i did it messed up those spells.
That solution worked for me, hence the excitement to share it ( I bet you guys write miles of lines of code in a finger snape
), but I couldn't figure out how the class bitmask worked .. Thanks for the help on that Uleat !