If I add, e.g., a new .cs file to a visual studio project (.csproj file), or similarly for other popular development environments, SourceTree should be able to detect automatically that this new .cs file must be added to source control when I stage/commit. Many times I've had builds fail on our ci system just because I've added a new reference to a file to a project file but forgotten to add the file itself. The visual studio git integration does handle this automatically but unfortunately doesn't work well for me for other reasons.