How do I select
the source file if context menus aren't available on my system?
You will have to
manually open the application, select the files you wish to transfer from
an Explorer window, and drag-and-drop them into the application. Do note
that when you start the transfer, only the last dropped files will be
transferred. This means that if you drag-and-drop files into the application
several times without starting the transfer, only the last dropped files
will be transferred.