RectangularPaletteControl has 'open' function but not declared is 'open'

[iChezee]

Discussion: RectangularPaletteControl has 'open func setHue(horizontalAxis: Bool, updateImage: Bool)' but not declared as 'open' itself. So you cannot inherit from RectangularPaletteControl directly and you need to reimplement it's behaviour using ColorPaletteControl. If I will just copy-paste it's code there other things that is closed to override too. Or, for example, I want too use RectangularPaletteControl but override some open functions from ColorPaletteControl I cannot do that.

Suggestion: Make RectangularPaletteControl 'open' to inherit too.