Created attachment 187151 [details] Shapes showing the problem of faulty black color Open attached document. It has four shapes. The shapes use a gradient with color stops at positions 0, 0.4, 0.7 and 1. The shapes only differ in the value of color stop at positions 0.4. The colors at position 0.4 and 0.7 are the same in first shape. The colors differ by 3 in the green component in the last shape. Those shapes are rendered correctly. The shape in between differ in by 1 and by 2, respectively, in the green component. They show the wrong black part between the stops. The problem is not academic but real, namely some Smartart shapes use fillings with such small color differences. Armin: Can you give a tip, in which area to search for the reason?
Sorry for the noise. I have just tested with a build started today afternoon. The error is gone :) It is likely fixed by https://cgit.freedesktop.org/libreoffice/core/commit/?id=db4b960643832a52000523ca2eb3667e36af52cd from today morning.