It actually is fixed - I tested it a couple days ago, and now the window decorations are not distorted independent of the $QT_GRAPHICSSYSTEM environment variable (either "native" or "raster" works).
It actually is fixed - I tested it a couple days ago, and now the window decorations are not distorted independent of the $QT_GRAPHICSSYSTEM environment variable (either "native" or "raster" works).