Fix visual bell
Changes to scrollbar colouring interfered with the visual bell. TerminalColor::onColorsChanged() not only updates the scrollbar palette (for Breeze widget style), but also updates the TerminalDisplay palette.
Changes to scrollbar colouring interfered with the visual bell. TerminalColor::onColorsChanged() not only updates the scrollbar palette (for Breeze widget style), but also updates the TerminalDisplay palette.