I'm not sure if this is not a duplicate of SRCTREEWIN-897, but I find it pretty dangerous that SourceTreeApp in version 1.3.1.0 let you commit on a detached HEAD without a warning.

This happens often when people work within submodules, makes a commit of the top-level project and get the "Submodule Check" window that tells to commit changes in submodules, then they do so and get their new commit on no branch, just pointed by HEAD because they didn't checkout any valid branch before.

It's the default git behaviour to checkout the referenced commit of a submodule as detached HEAD and this is not possible to change, but it's IMHO really important to warn the user that he is commiting on a detached HEAD.

Git gui warn the user after clicking commit, which isn't the case of Source Tree App, and I think this would be nice, because people tends to "loose" their HEAD in such cases.