Recently I've been critical of the sidebar/blade menu, especially when it comes to settings level. The main reason for this is that there is no indication to the user that is visible right away to tell them something has changed. This isn't a new issue though, and there are a few other areas of XBMC that we do this:
• Hide watched - Even the best of us have gotten tricked by forgetting we enabled "hide watched"
• Repeat - Should be indicated at least on the OSD when enabled.
• Shuffle - Should be indicated at least on the OSD when enabled.
• Basic playlists/queue - queue a show but nothing visually changes. People expect some kind of feedback, else they assume it was a miss-click or error, etc.
and likely more.
The use of small visual indicators or cues can go a long way in helping make XBMC easier to use, as well as help people figure out why something is acting differently. These don't even have to be hit-you-over-the-head spelled out. Even an unexplained indicator or icon at least tells the user "something has changed" and can be a great help. I don't think this is a case where the user should be expected to go online and read a manual. The natural assumption when things disappear is that they are gone or something went wrong, and not that they need to look for a button in a hidden menu. The button can still be located in the slide-out/blade menu, but some visual feedback, even something very subtle, will make a big difference.
How to actually do this, and in a way that looks good and doesn't get in the way, is the challenge.