i use to create a full transparent form, but the png and the 32bit image will not blend to the form and images is not properly displayed its trnsparency. i get the concept h
Seems that Andreas Hausladen stumbled upon a similar problem and has already implemented a solution: he rewrote TJvTransparentForm in the JVCL library.
Even if you are not going to use that component directly you may gain some insight by studying the source.