The Problem
One of the benefits of working with Studio is that it is unique amongst CAT tools in providing Document Structure Information that can be used to help provide additional context when translating. The downside of this feature is that you have to actively click the DSI column to see this information for each segment and you can't work on the translation while it is being displayed. The same thing goes for comments which can only be seen by scrolling through the comments view.

The Solution
The DSI Viewer solves this issue by providing you with a small viewer that you can position somewhere convenient on your screen and this displays the DSI information and comments for every segment you enter without you having to click anything.
Very handy when working with DITA files, custom XML files or even SDLXLIFF files that have been exported from SDL Passolo (these contain string IDs that are very useful when translating).
It's also particularly useful when working with Bilingual Excel files as these support the ability to add information from the Excel file to the Document Structure Information and/or comments.