Create window from arbitrary pixmap as background

[Lucas de Sena]

On 2024-07-20, Carsten Haitzler wrote:
> well this is a different thing - that pxiamp is provided by some other client
> so you have fairly little choice. it's a bit primitive TBH especially as you
> now don't have alpha - this is why the freeddesktop extended hints provide an
> icon RGBA data property ... much nicer :)

PS: Is it possible to "convert" a pixmap with a given depth into a
pixmap with a (lesser) depth?  How?