Code to catch and access DOM of an item dragged from File Explorer and onto Internet Explorer or FireFox window

I'm not sure what technology would be best for that, but the behavioral goal is that the HTML DOM from? the Internet Explorer or FireFox window that a file was dragged and dropped onto must be accessible from C# code. I'm sure this could be accomplished by writing both an Internet Explorer and a FireFox add-in or perhaps just some coded hooked or injected into the windows memory space but it doesn't matter to me. I just want to be able to manipulate the DOM as that action occurs.