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VBDT Global Windows Hook
Yaca, Clipboard little helper.
They use Windows Hook to get a handle on the clipboard, you can then determine when an object is copied and when it is pasted.
You can get the content of the clipboard if it contains a Filepath like this.
using System.Collections.Specialized;
StringCollection files = Clipboard.GetFileDropList();
if (files != null)
{
foreach (string file in files)
{
MessageBox.Show(file);
}
}