Update text color based on system color scheme

[feifanzhou]

Hello! In the STTextViewUI.TextView example, the text color doesn't change when the system color scheme changes, leading to a default of dark text in dark mode:

I attempted a naive fix, but it has no effect on the preview. I'm happy to investigate further if you have some pointers about where to look.

It looks like colorScheme is referenced in TextView, but isn't used anywhere. Was this meant to be used somewhere?

[krzyzanowskim]

It looks like this is the Demo app issue. The problem is that AttributedString by default doesn't have any text color set. If we explicitly set the NSColor.textColor to it, it going to update as expected:

AttributedString(string, attributes: AttributeContainer().foregroundColor(NSColor.textColor))

I'm going to update demo app code with this

[feifanzhou]

Ah yes, that change did the trick — thanks!