As reported the issue on vram-guild/canvas#395, when these two mods were working together, GUIs like Inventories and GUI items flicker like the end of the world.

I'll disable the screen part next update anyway(at least by default). Canvas is currently not on my list of mods I plan to actively support(same as optifine), so don't think it will be any prio to fix a bug of a broken feature for an unsupported mod.