I noticed that Cairo offers a function called `cairo_paint_with_alpha`, that accompanies `cairo_paint`, (http://cairographics.org/manual/cairo-cairo-t.html#cairo-paint).
At present Julia's Cairo.jl doesn't seem to have this defined. Is it possible to test it out by defining it using `ccall`, but without adding it to Cairo.jl? I was thinking something like: using Cairo function paint_with_alpha(ctx::CairoContext, a = 0.5) ccall((:cairo_paint_with_alpha, _jl_libcairo), Ptr{Void}, (Ptr{Void}, Float64), ctx.ptr, a) end which doesn't work, obviously, cos I'm just guessing at the syntax... If it works, it could be added to a pull request.