The Context Window is a Source Insight innovation that automatically provides you with relevant information while you are viewing and editing your source code.
The Context Window is a floating, dockable window that displays contextual information while you type or click on things. For example, if you click on a function call, the Context Window will display the function's definition. If you start typing, the Context Window will display a filtered list of symbols in your project that match what you've typed.

You can toggle the Context Window on and off by running the Context Window command. The Activate Global Symbol List command makes it visible and then sets the focus on the Context Window edit field so you can type the name of a symbol to locate it in a list of symbols, similar to the Browse Global Symbols dialog box.
The Context Window Tracks What You Do
Decoding Base Types to Show Structures
Customizing the Context Window