The 3rd Party Library Paths settings allow you to configure how Visual Studio Project Builder identifies third party libraries.
When Visual Studio Project Builder is optimizing the project build order, it needs to identify libraries that are not part of the build process, but which are supplied by Microsoft and by third party software vendors. The Visual Studio Paths part of the settings dialog supplies (indirectly) the paths for the Microsoft libraries. For third party libraries, the paths to these also need to be provided. That is the purpose of the Third Party Library Paths settings.
To remove a library path, select it then click Remove.
To clear the list, click Remove All.
To add a library path, click the Add... button which will display a Microsoft Directory Browser to allow you to find and select a directory.
To edit a library path, select it then click the Edit... button which will display a Microsoft Directory Browser to allow you to find and select a directory.
Any library paths which no longer exist (they have been deleted, or moved, or renamed) will be displayed in red.
The Reset button will cause the settings on all parts of the settings dialog to be reset.