Extending the TreeView control in .NET to allow selecting multiple items. This repository is migrated from SourceForge ".NET Multi-Select TreeView 2": https://sourceforge.net/projects/mulsel-treeview/?source=typ_redirect
The original / bulk of the work was ".NET Multi-Select TreeView": https://sourceforge.net/projects/mstreeview/ but I was unable to reach them when I made some bug fixes etc. so I spawned the above SourceForge repo.