when using the set_context function, there are several contexts available to you. They are:
ZP_INDEX
ZP_ALBUM
ZP_IMAGE
ZP_COMMENT
ZP_GROUP
I'm not too sure as to what the group context is all about since I haven't delved into the new code yet, but let's take the album context as an example.
Themes will have an index.php -- this file shows a listing of all the albums. When you click on one of the albums, you're now using album.php. This is basically what handles the display of the albums page (where all the thumbnails for the images are shown). It is in this file that your context is automatically set to ZP_ALBUM. This allows album.php to have access to all of the functions that affect albums such as getting the album's title, getting the album's date, getting the album's thumbnail, etc.
In your case, you'll want to manually set the context to ZP_ALBUM but you'll want to do that inside index.php. The context that is automatically set inside index.php is ZP_INDEX. This means that you won't have access to the album fucntions. This is why you'll need set it manually.
So, you use the set_context() function by the following:
`... <normal index context code> ...
set_context(ZP_ALBUM);
<album context code>
set_context(ZP_INDEX);
... <resume normal index context code> ...`
That's all.