Hello,
interesting issue, but it is very specific to the Fancybox UI.
the arrows seem to pop up when you reach the photo border with the mouse, so there should be some Jquery code for it in the Fancybox code.
If there is an option for making them permanent in Fancybox it shouldn’t be a problem to ingrate it in the plugin-generated code. But if not, it could be kind of difficult.
I gave a quick look to fancybox.net (Simplest Gallery includes that code) and there is an option showNavArrows but it does not say it makes them permanent. I woud guess this option is already active in the plugin’s implementation.
I think that some tweaking with the jQuery code is needed, but I can’t help you on this because it’s beyond the scopes of this free support forum.
If you have news on th issue, it could be of public interest anyway.