Hello.
I've seen in many themes that plasmoids can be transparent without having the effects enabled. Even in my favorite plasmoid (Customizable Weather Plasmoid) you can adjust the transparency level. Then, the transparency of the panel with the effects disabled: Is this an unsolvable limitation in the panel code or simply has not been implemented?

When I refer to "transparency" I mean a basic transparency, no blurring of course.

Thanks.

Real transparency is not possible since the panel runs in its own window (I think I use the right terminology here). For example, you can drag a normal window below the panel. From this you can see that the panel doesn't live on the same "scene" as the desktop widgets.

Fake transparency is possible but not implemented because it's considered a hack. I think some distros, such as Chakra, has patched the source to enable fake transparency when compositing is disabled.