This is a reminder of a couple of problems that I’ve come across a few times – that the breadcrumbs in LAYOUTS pages and central admin are a bit tricky.
Breadcrumbs in Layouts pages are driven by an XML file in your IIS web app. Now, you can add entries which are merged into that – a described by Jan Tielens’ Adding Breadcrumb to application pages in SharePoint – the easy way. However, this doesn’t cover the whole problem – he goes on to describe dealing with Central Admin too.
However, the really tricky bit of this that though we can define our own sitemap.xml file, it’s kind of hard to merge with the existing one. Specifically, the problem is that to merge ‘our additions’ and the ‘existing file’, we have to call a function ApplyApplicationContentToLocalServer, and as brilliantly described by Sean McDonough, the word ‘local’ is a problem in this method – it only forces a merge of the files on one server. Not much use in a server farm.
Sean’s article describes his attempt at a fix – using a one-time timer job, and a fair bit of reverse engineering of the ApplyApplicationContentToLocalServer function. Also, it seems like Vince Rothwell has come up with a similar solution, so it’s likely that this is a good approach.
A real pain to have to build so much to do such a simple task, though.