How about custom colors/graphics in the FX window ? Logic plugins and instruments... aii
And one more: easier GUI coloring
1) you open a "color this element" window with a palette,
2) while you move your mouse over GUI elements, they (as a preview) change colors to the selected one (following mouse focus).
3) When you like the result, you click your mouse and the color is set.
4) If you close the palette without clicking, no change is made.
5) And of course there would be a toggle in the palette window between changing colors of the GUI, and changing only item colors (for instance to color-code them and be able "select every item of the same color")