This addresses the Oxygen Transparent theme, which is not included with mainstream KDE although developed by the same team. I'm not certain whether this bug tracker covers such a component, but I'm opening this in case it's a legitimate request. I've used Oxygen Transparent for a long time, as I'm a fan of the transparent blurry titlebar and window contents. With KDE4 on its way out, I'm wondering if this ability will still exist in Framework 5 and the new Kwin. The current oxygen-transparent package is no longer listed under Window Decorations after upgrading to the KDE 5 packages, and would likely be incompatible with the latest implementation. Please port the transparent version of the Oxygen theme to Framework 5. Or allow the mainstream Oxygen theme to optionally support transparency and blur, in case that would be an easier or more adequate approach. Reproducible: Always Alternatively, it would be nice to see a transparent version of the new default theme (Breeze Transparent). As well as builtin support for widget transparency (currently dependent on liboxygenstyle-transparent) in case transparency is simpler to implement under the upcoming framework.
Oxygen-Transparent is unmaintained, so we unfortunately have to close all tickets. Other style engines (QtCurve, Kvantum) might also offer transparency.