With 5.0.0, the theme problem are fixed.
With older releases, theme files come originally from KDE settings panel. link to KDE setup was available in DK menu. This rely in-deep with with KDE desktop.
With 5.0.0, the dependency to KDE desktop was removed and file customized theme have been integrated in DK as well. A fix taken from Krita (who deal in the same way with theme) have been applied to prevent widget colors glitch when themes are applied to whole application.
Best
Gilles Caulier