Will Apple reject an app which renders a 3D scene that allows you to modify and compile GLSL ES shaders by editing them in the app? (something not unlike e.g. http://shadertoy.com, but native OpenGL ES 2)
What about if it registers for a file type and opens .vsh and .fsh files as documents?
I know that it may be problematic if the app automatically downloads shader code from a server (and then runs it), but the answer is not so clear for these other approaches.