I'm having trouble creating custom colors in Prism Windows

The custom color dialog in Prism Windows is a standard Windows dialog that we don't have control over. Creating custom colors is easy but perhaps not as intuitive as it could be. Here is what you need to do:

1.) Select "More Colors" from any basic color dialog to open the Custom Colors dialog.

2.) Click on a blank (unused) box in the Custom Colors section.

3.) Click on a custom color from the color palette.
4.) Pick an Intensity setting for your color on the slider bar on the right side of the window. 
5.) Click "Add to Custom Colors"