3ds Max scene files can be dropped from the Windows desktop or Windows Explorer.
3ds Max behaves differently depending on whether the file is dropped on a viewport or anywhere else in the 3ds Max UI:
When dropping .max scene files onto a 3ds Max viewport, either from i-drop-enabled web pages or directly from file directories, the Open/Merge/XRef/Cancel pop-up menu is displayed.
If the scene file is dropped elsewhere, such as on the toolbars, menu bar, status bar the file is opened, closing the currently open file.
Dropping a scene file on the Command Panel does not perform any operation.