For the pending files can not set tree view to display files, the feature is removed.

Jason Chen3

The pending files can be set tree view for display stage files before version 1.8.2, Could you add this utility feature. Thanks. 

Seth

Tree view was intentionally removed as of version 1.8, presumably because Atlassian could never resolve its performance issues. Sounds like Atlassian has plans to re-introduce it when they get the issues resolved:

https://jira.atlassian.com/browse/SRCTREEWIN-4690