Determines whether a drag operation can proceed. This method is required for a browser to be a drag source.
- macOS 10.5+
The indexes of the rows the user is dragging.
The index of the column containing the dragged rows.
The pasteboard containing the content from the dragged rows.
YES to allow the dragging operation to proceed (see discussion for further details);
NO to disallow it.
This method is called after a drag operation has been allowed to start (
YES), but before it actually begins.