Slider should work even with 1 slider

[laulaz]

If you have 2 sliders on your site, then remove one of them, the viewlet doesn't display the slider anymore (len(context.slider_relation) > 1 & len(banners) > 1).

It should work, but without the next / previous arrows.

[mtrebron]

The 'Banner' behavior is intended for single slides. I agree with you that this distinction is unintuitive. Removing navigation on a single banner could be done in the viewlet template.