No transparency with floating panels

[TheRamsWay]

When using floating panels on Plasma 6.0 with the Willow Plasma style, panels have transparency only when the panel is defloated (when a window touches the panel) and is always opaque otherwise.

[doncsugar]

Thanks for reporting this one. It looks like in Plasma 6, there is a requirement for the panel-background.svg for the solid/set to have shadow assets in it. Adding shadow-center appears to have been enough for it to work.

I have not added a theme to the store for Plasma 6 yet, but the fixes are in 59b4e62.