Cannot draw anything transparent (non trivial alpha)

[1m1-github]

I am not able to produce a partially transparent drawing, no matter which value for alpha i use

example:

using MiniFB

WIDTH=800
HEIGHT=600
window = mfb_open_ex("My Window", WIDTH, HEIGHT, MiniFB.WF_RESIZABLE)

buffer = zeros(UInt32, WIDTH*HEIGHT)
alpha = 0
while true
    
    x = reinterpret(UInt32, [UInt8(100),UInt8(0),UInt8(0), UInt8(alpha%255)])[1]
    alpha += 1
    buffer = fill(x, WIDTH*HEIGHT)

    state = mfb_update(window,buffer)
    if state != MiniFB.STATE_OK
        break
    end
end

[1m1-github]

should add:
this is on newest macOS (M1) and newest julia

[1m1-github]

is transparency supposed to work? is there any example anyone can share please? ty

[aviks]

is transparency supposed to work

Don't no, really. Does it work in a simple C program? As you know, this is a simple wrapper around the C library.