Re: [Inkscape-user] Fill "only on one layer"

I know almost nothing about coding or programming. But to my simple way of thinking, that would be very complex feature. [...]

Not necessarily, actually*. The way the PB works is : - rasterize the visible part of the drawing - raster-fill that raster version - trace that bitmap fill

(which is why it is such an non-exact tool on vector parts when you look closely)

The only change that would be involved would be to rasterize only the current layer, same as you can alt+b any selected group even if there are other items in front (layers are only groups, after all).

I consider the PB tool to be a nice way of "quickly trace" patches on imported bitmaps, but not much more than that, so I completely agree with your "better practice" advice.