Flaky Side Panel edit behavior

Somehow we've got wiki fablabsd into a state where the Side Panel editing feature (Settings > Customization) is not working properly.

By the time you read this, it may or may not still be broken, but I will describe the current symptoms.

The core symptom is that adding the Incoming Links widget (followed by Save button of course), has no effect on the wiki display, and the Incoming Links block is missing from the DOM (td#incomingLinks).

More destructively,I have seen the wiki get into a state where if I delete the Incoming Links widget from the Customizations display Side Panel (and it indeed disappears from there), the result is that on an actual page, some other widget disappears instead!

Some series of steps seems to recover from this worst behavior, even though adding the Incoming Links widget continues not to actually show the widget on a page.
At the same time as all this, on a subsidiary workspace with its own Side Panel configuration, everything continues to work as normal, including Incoming Links widget, and including adding and deleting that widget.

So at the moment I'm stumped how to get Incoming Links back on to the main wiki, but the more important point is that there's something flaky that needs looking at.

- Graham

My issue tracking id GWZ1018