Other - Native Files
A drop target can accept OS-level drags by listing a BdndNativeTypes value. Here
the target accepts BdndNativeTypes.File; drag files from your file explorer onto
it and the OnNativeDrop callback receives the file list.
Drag files here from your OS
Only file metadata (name, size, MIME type) is exposed by the browser during a drop;
reading contents would use an additional file API.