If I use this theme: http://kde-look.org/content/show.php/Co ... ent=156954

or this window decoration: http://kde-look.org/content/show.php/Ai ... lack%20%20[AURORAE]?content=108353

The semi-transparent elements appear completely transparent. Is this a limitation of Plasma 5 or is it a config issue/missing package?

I am running KWin4 if that may be the issue?

It can be that kde4 themes are not compatible with kf5 themes.