[Lazarus] TBitBtn image, how to make background transparent?

[Bo Berglund]

I am trying to make a bitmap image for a TBitBtn button such that the
background of the image will be transpoarent and therefore the button
color will be visible.

But I don't succeed with this, the background I use for the image is
visible on the button.
Even if I set the same color as the buttonface to the background it
becomes visible on the button because the button itself has gadient
color....
So not the same color at the top of the button and at the bottom.

I was under the impression that button images use the color of pixel
(1, 1) as the define for the transparent color, so I have the complete
border set to the same background color.
Not working....

Or is a specific color defined as the transparent color, if so what is
this color? (RGB please)

What can I do to use glyphs on a TBitButton?

-- 
Bo Berglund
Developer in Sweden