The only problem I can think of at the moment is that your PNG image will not be scaled when navButtonIconSize is used.

However, if navButtonIconSize is used, then the navigation button background (the semi-transparent grey circle) will be scaled and, if it is large enough, it will become visible behind your PNG image.
To counteract this, you can make the navigation button background completely transparent by setting navButtonBackColor="rgba(0,0,0,0)" (in JuiceboxBuilder-Pro's 'Customize -> Color' section).

Otherwise, as long as your PNG image looks OK in both Small Screen Mode and Large Screen Mode, I do not see any other obvious problems or pitfalls.

You're welcome!

Just to clarify, the main image navigation buttons would appear in Small Screen Mode/Touch Input Mode only if you set showImageNav="ALWAYS" (in JuiceboxBuilder-Pro's 'Customize -> Main Image' section).
When showImageNav="HOVER" (the default value), the main image navigation buttons would be hidden in Small Screen Mode/Touch Input Mode (in preference to the swipe gesture for navigating between images).

That's correct. Instead of saying "in Small Screen Mode/Touch Input Mode" I should probably have said "in Small Screen Mode and Touch Input Mode (the combination used on an iPhone which you referred to)".

For other users reading this thread, more information about Screen and Input Modes can be found in the Gallery Tour.

I'm not sure if you are specifically referring to thumbnail or main image navigation buttons but the current configuration options which change the visibility of the navigation buttons are:
showImageNav (which affects the main image nav buttons in both Small and Large Screen Modes) HOVER/ALWAYS/NEVER
showSmallThumbNav (which shows or hides the thumbnail nav buttons in Small Screen Mode) - TRUE/FALSE

Unfortunately, there's no configuration option available which would allow you to change the visibility of the navigation buttons for a specific Input Mode.

If you wanted to try to hide navigation buttons when they would normally be visible (for example), then you could perhaps detect which Screen Mode is currently being used (via the Juicebox-Pro API getScreenMode() method) and then implement some custom CSS and JavaScript to override Juicebox-Pro's own handling of the nav button visibility.
This might be fraught with difficulty (there are often unforeseen knock-on problems with such modifications) and I would not recommend it but you are free to try it if you like.
Please note that there is no Juicebox-Pro API method to determine which Input Mode is currently being used. You'd need to write your own routine to detect whether a touch screen is in use (if you wanted to).

Thank you for posting your suggestion in the Feature Requests forum thread.
It will certainly be seen by the developers there.

Steven,

For information, and to help others, thumb nav buttons can be made to disappear from Large Screen Mode touch screens e.g. iPads, without (so far) unintended consequences:

    <script>
        var jb = new juicebox({
        containerId: 'juicebox-container'
        });
        
        var is_touch_device = 'ontouchstart' in document.documentElement;
        var touch_status = (is_touch_device) ? 'touch' : 'no-touch';
        var screenmode = jb.getScreenMode();

        jb.onInitComplete = function(e){    
            if (screenmode == 'LARGE' && touch_status == "touch"){
                    $('.jbn-right-button, .jbn-left-button').css('display','none');
                };
            }
        
        jb.onThumbPageChange = function(e){    
            if (screenmode == 'LARGE' && touch_status == "touch"){
                    $('.jbn-right-button, .jbn-left-button').css('display','none');
                };
            }
        
      </script>

When a Gallery opens, the right thumb nav button briefly shows (unintended but appropriate hint to users to swipe) then disappears.

This may make my feature request superfluous: detecting touch screens is said to be unreliable however it is done, but it works for me...

Regards,

Brian