When you add a layer to something, you tend to add it on top of what's already there. In helioviewer.org, this is reversed - new image layers get added underneath what is already there. That doesn't make much sense.
I recommend changing this behavior for helioviewer.org. When adding a new layer, the new layer should be prepended to the existing images (see screenshot below) and the new layer should appear at 100% opacity on top of the existing layers.
When you add a layer to something, you tend to add it on top of what's already there. In helioviewer.org, this is reversed - new image layers get added underneath what is already there. That doesn't make much sense.
I recommend changing this behavior for helioviewer.org. When adding a new layer, the new layer should be prepended to the existing images (see screenshot below) and the new layer should appear at 100% opacity on top of the existing layers.