I wrote short testing code which should use the hidden matrix to hide 5 objects at the screen.
Either I don't understand something, or the hidden matrix is broken. By default there are zero areas at the screen. I know it for sure, because for testing I created them with 500x500 size, impossible to miss. But once I changed alpha of hidden matrix buttons to 1, there is always one single area at the top left corner, with zero randomness. Even though the corner is always empty with the old alpha = 0.001.
I dunno why your hidden matrix acts like that, even if I gave it incorrect dict somehow, it acts differently with different alpha.
I had the very same issues when tried to use it for fishing screen before making different screen with imagebuttons.