Filedrag plugin installation
CCSv4 is based off Eclipse 3.2, which does not support drag-and-drop of files into the editor. However there is an Eclipse 3.2 plug-in called 'Filedrag' that can add support for this in CCSv4. 'Filedrag' is part of Sunshade, a suite of plug-ins for the Eclipse IDE. Because some of the other plug-ins that are part of Sunshade require a JDT which CCSv4 does not come with, the Eclipse update manager cannot be used to install Sunshade.
Obtain the Sunshade Plugin
Download the Sunshade zip (make sure you download Sunshade for Eclipse 3.2)
Extract the zip in a temporary folder. Then Copy just the 'plugins' folders contained in the zip into the '.\ccsv4\eclipse' folder. Do NOT copy the 'features' folder into CCSv4 as this will cause problems with the Eclipse update manager.
Note that for Windows, you need to drop the file into the title bar of the Eclipse window and not into the editor itself.