If you change the background color of the slideshow a second time, then it is not applied, the first set color remains.

How to reproduce:
1. go to admin settings: mod_lesson then change setting mod_lesson | slideshowbgcolor to #1fa2ff. Save settings.

2. Create lesson, set slideshow -> true.

3. Create a page, go to view it and see the background color set in the settings - #1fa2ff.

4. go to admin settings: mod_lesson then change setting mod_lesson | slideshowbgcolor to #ff1fbf. Save settings.
5. Go to view lesson page and we see that the color has not changed to #ff1fbf.