In order to make the program easier to understand, a few things have been moved or renamed.
What was called "Document Options" in version 3 is now called File Type Options. It contains all file-type specific options. For example, there is a file type named "C/C++ Files". The "Document Type" term has been replaced with "File Type". See: File Types.
The C and C++ file types have been merged into just "C/C++ Source File"
What was called "Draft View" in version 3 is now called "Mono Font View"
What used to be called "symbol syllables" in version 3 is now called "name fragments".
Dock-able/Floating windows are now called Panels. Besides the Context and Relation window, there are a few new panels, such as FTP Browser, Window List, Snippets, Bookmarks, Directory Compare, and File Compare.
Project Files - the new extension is .siproj for the main project file. All the data file formats have changed from version 3. You can still open version 3 projects, but they will be converted to the new format.
The Project Symbol Path idea has been replaced with Project > Import External Symbols. This feature lets you import symbols from external sources, such as header files, .NET assemblies, and Java jar files. Each time you import something, Source Insight creates a special "import" project for you. It will automatically search for symbols there. You can still use the project symbol path if you want. See: Importing Symbols from Libraries.
Project Settings now has a "Backup Directory" option. By default, each project gets its own backup folder under its project folder.
All projects share the same configuration settings now. However the configuration file system has some flexibility when it comes to project-specific configuration parts. See: Customized Settings and Configurations.