I'm using red colors (hue = 0 in HSL mode) for later recoloring. This way I can recolor textures into any color I want using color rotation for the hue value. This can be useful for making a new color theme or adjusting UI colors to fit the background image. Inkscape uses range 0-255 for the hue values, but ImageMagick uses 100-200 for it's modulate operation. So I'm converting Inkscape color's hue value into ImageMagick one this way: hue / 255 * 200 + 100.

Screenshots of the refined UI with a new widgets