Interesting little problem ;)
What's happening is that your black frame color is overriding the settings for Image Nav Color and Thumb Nav Color whereas it should be the other way around.
I'll fix this in the next release of svManager but in the meantime here is a workaround.
Go into the svManager pro screen, open up the Image overlay section and change the Image nav color to FEFEFE. Don't use the color picker, just type it in. FEFEFE is very, very nearly white, you won't see the difference but it will fool svManager into saving the setting because it is no longer the default.
Then open up the Thumbnail navigation section and set the Thumb nav color to FEFEFE.
Click the Update all button.
SimpleViewer Support Team.