the mask thing which is basically an eraser in form of color do not with lock alpha and alpha compositing in the rgb mode, the alpha compositing indeed work in de indexed mode but the lock alpha still dont work. and i think that not being able to use mask in the rgb mode only with simple ink and copy alpha+color is very troublesome since the mask is such an useful feature.
That’s because in indexed mode one of the palette colors is set as transparency (index-0 by default, identifiable by the little dot in the middle of the color in the palette), so when you are drawing mask in indexed mode you are actually drawing that color.
However in RGB mode we have true transparency, in which case both lock alpha and alpha compositing inks are meant to function in certain ways with alpha, and mask is simply just a 0 alpha “color”. So when we use inks that are meant to blend or ignore alpha, it does nothing.
so its impossible to use the mask on alpha compositing because it treat the mask as a color with 0 transparency but why we cant use the lock alpha function, its doest make sense because if i use simple ink and copy alpha+color it works. mask should be a specific type of “color” ist kinda odd that ts simply treated as a 0 opacity color?
sorry english ist my native language so something is probaly wrong here.