Edit Menu Commands

Undo Reverses the last editing action, if possible
  Redo Reverses the effect of the last Undo command
  Cut Deletes selected text from the active window and copies it to the Clipboard
  Copy Copies selected text, without deleting it, from the active window to the Clipboard
  Paste Copies text from the Clipboard to the active window.
  Delete Deletes selected text
  Find Searches the active window for a text string.
  Replace Replaces one text string or regular expression with another.
  Read Only Prevents changes to the active window

If no source windows are open, Edit menu commands are unavailable and thus
appear dimmed on the menu.