The “flexible” panel spacer has a static size. The “flexible size” has no effect. Reproducible: Always Steps to Reproduce: 1. Add a “flexible” spacer 2. Add a new widget (or get a new tray icon) 3. See things disappearing because the spacer didn’t resize
Should be fixed by 8e1339887a01e078b04fb18ff575c16998447665 which is in Plasma/5.8