I see @Christian Brinkmann (poor) suggested the Render Border as good candidate for widgetification (+1 from me), but I think maybe you missed this suggestion @Campbell Barton (campbellbarton)?

Hi. Seeing as it was asked, I just thought I would chip in and say, yes, there is another add-on that does this (though it works on a 0-1 scale instead of pixels), my 'Animated Render Border' add-on: https://blendermarket.com/products/animated-render-border/ .

The correct tagging of information allows said information to be accurately searched, which from a user perspective is important to be able to find existing bugs to prevent reporting duplicates. Personally, I would also think it's important from a developer perspective to make sure the ever important bug list is not populated with things which aren't bugs, but then I'm not a developer. I'd say this sounds more like a task, but if you're saying it's a bug, fair enough.

Is this meant to be tagged as a bug?

I notice that this and a few other documentation tasks are of type 'Bug', but shouldn't they be 'Design' when they are about discussing changes?

@Sergey Sharybin (sergey) Ok, thanks, I thought it may be a dependency graph issue. I just thought it was weird that 'emitter' particles updated their colour, but 'hair' didn't.

@Philipp Oeser (lichtwerk) Yes, I understand I can access the points and calculate the bounding box manually, the main point of this report was to say that if the bounding box option is available I expect it to update and if 'bound_box' is available in the api, I expect that to return correct values (which I also expect for the other object types I mentioned).

@perfection cat (sindra1961) I'm not sure what I should be looking at on that page.

Meant 2.75a.

Yep, changed to US keyboard language and it worked.

As I said in my original report, I tried this on a separate windows 8.1 machine. I have since tested:

Ok, so I just found that if I press the apostrophe key ( ' on the same key as the @ symbol) I can toggle all the layers
(I'm using a standard UK qwerty keyboard). I was under the impression that it is the backtick key ( ` ) commonly found above the 'tab' key and to the left of the '1' key that should be toggling the layers.

This may be a similar situation to what @Karja Krähwald (karja) said above, but particularly when modelling wheels/tire tread it is necessary to merge the beginning and end of the tire to create a complete circle.

@Campbell Barton (campbellbarton) Ok, thanks for clearing up how it works, that helps.

Ah sorry, forgot this:

Blend File: