Notepad++ Plugin

I need a Notepad++ Plugin for the "Folder as Workspace" area, a File Tree display of files. The current functionality when clicking the file is to open it in Notepad; and a right-mouse-click to pick from the pop-up-menu to Run As System (meaning open the file based on it's extension). Since I have all .txt files opening in Notepad++ anyway, and opening a .pdf in Notepad++ makes no sense, I'd like it to work differently.