[acedio]

Tried seeing how small of a program I could fill the screen with. Came up with this, but feels like there has to be a more elegant solution ^^;

[[[[[[[[[[[[[[[[F]]]]]]]]RRF[[R]R]]]]]]]]]

[vitus]

Naive micro-optimization of your program (namely, things like FF is 1 char shorter than [F]) got that down to 40 chars:

    [[[[[[[[[[[[[[[FF]]]]]]]RRF[RRR]]]]]]]]]

I then found a solution in 37 which uses a slightly different approach (namely, create a pattern that spans the full X and Y output space, then shift it by one step each iteration):

    [[[[[[[[[[[[[[[[FFF]]]]]R]]]F]]]]]]]]