RGB color chooser resets hue to red when set to gray

[Kyuuhachi]

When a RGB color chooser (for example via color_edit_button_rgb) is set to a gray shade (the left or bottom edges), the hue is changed to red. Presumably this is because the color is stored in the user-provided variable, which is RGB and thus cannot store the hue in that case. The best solution I can think of is having the widget store the hue separately (only used if the color is grayscale).

[emilk]

This is already implemented for color_edit_button_rgba_&, just not for color_edit_button_rgb (yet) due to laziness.