Since compiling's inception software development has been limited to computer artifacts of files and folders. This has always caused problems when groups of developers have to work together to write an application. All configuration manager programs suffer from the same problem. A file unfortunately crosses conceptual (read: OO) boundaries. IMO, the only way for the IDE to go to the next level of usability is to eliminate files and folders so developers can develop simultaneously without the need for merging afterwards. Let each developer have r/w access to a concept (class/struct/methods/functions/?) at a time while other areas are r/o. Same goes for the other developers on the project only they would be developing in other complementary conceptual areas. Conceptual areas would be non-overlapping. Presto, no more merging.