The problem arises if you mouse over a color that is already added to your custom colors. Say you have the windows background added as your first color and you want to add the title bar color as your second. You select the second box (which should be the default white color) and press the pick screen color button. As you mouse over the windows background, the first color is selected in the color dialog. The problem comes when you finally get to the title color. After you click it and click the Add to custom color button, the first box (which should have the windows background color) is replaced instead of the second.