When application palette is changed at runtime (rather than at startup), the palette changes are not propagated correctly to all widgets. For example `QSpinBox`, `QComboBox` and `QTreeView` and maybe some others are not correctly updated, while most widgets are updated fine.
See https://stackoverflow.com/questions/47971350/change-application-palette-run-time-without-restarting-the-application for source code to replicate this wrong behaviour. Observed on Windows 10, but I expect the same on other platforms.
For example I started the application with 'dark' fusion theme:
But when I switch the palette to standard fusion 'light' scheme at run-time I get this: