Graphical: Copy formatted text, paste it in the graphical window to see what you copied formatted how it was, OR paste it somewhere else to get the markdown of what you copied. You should be able to paste in a markdown snippet from an external source and see it graphically.
Markdown: Cannot be edited but can be highlighted and copy/pasted to anywhere else including the graphical editor.
Graphical: Copy formatted text, paste it in the graphical window to see what you copied formatted how it was, OR paste it somewhere else to get the markdown of what you copied. You should be able to paste in a markdown snippet from an external source and see it graphically.
Markdown: Cannot be edited but can be highlighted and copy/pasted to anywhere else including the graphical editor.