Macintosh only: With a Macintosh one-button-mouse you have to simulate pressing the right mouse button by pressing Ctrl. Press the apple key for copying instead of moving the block.
OS/2 only: You are also allowed to drag text file icons to a specific
position of the text area. This will read the file. If you press SHIFT while
dragging, the name of the file without directories is copied instead of the file
content. Pressing CTRL-SHIFT copies the whole filename with directory names.
Reverse, you are allowed to drop marked text to a desktop folder. You will automatically
get a filename, based on the beginning text of the marked block.
(I'm sorry, but Windows does not offer such a functionality.)