Switching theme bug when custom controls are grouped

[splash21]

I found a bug today when switching themes : it happened when I grouped some icon buttons together then tried to switch theme. The custom controls being inside a group caused a problem with the theme switching. I've already recoded the theme switching to take account of grouped custom controls, so I'll just do a further bit of testing and then post the update.

Always a good idea to save before doing anything that makes multiple changes to your controls - and, thankfully, I did!