I have to disagree Bruno and sorry to say, what you suggest is not the solution, it makes the problem even worse.
Have you read my post, posted at 12:16am? I have already tried to apply the PNG to the "Picture" property and that only makes the problem worse as already explained 3 posts above this one (picture on the right) that the image moves up and does not get covered by the overlay color as it should (middle picture) and in addition to that also loses the alpha-transparency when the color is selected.
So using Picture property is not the solution, it makes the problem worse as I've already shown above.
Additionally, PNG is not applied to TImageList. TImageList cannot really store images. What I do is load PNG into TPngImage and then do CopyRect into Graphics::TBitmap created at runtime (the 32-bit TBitmap) and then finally copy such images into the TImage list (cd32Bit) with: bmp->AlphaFormat = afIgnored;
ImageList->Add(bmp.get(), NULL);
ImageList->Add(bmp.get(), NULL);
So the TImageList contains the 32-bit alpha bitmap and not the PNG. PNG is not the issue.
Additionally, it works fine - until the layer of color is applied on top of the bitmap which destroys the alpha transparency. So it works fine until the 4x16 block of selected color is added on the top of the icon - which should preserve the transparency, but it doesn't.
As I said already, this problem has been around for a few years now. It might not be trivial issue, I understand, but does it take a few years to get fixed?