The "Frame Colors" section is used to define a frame color for an element of the selected cart and for the element being read, if it exists. The color selection window is displayed when you click these buttons.
Main Background Color : general background color.
Selected Cart frame : color of the selected cart.
Playing Cart frame : color of the cart being broadcasted.
Normal Stack background : background color of the cartstack in PFL mode.
Onair Stack background : background color of the cartstack in Onair mode.