How can I add copy and paste support for my EditorWindow?

Very late, but I came across this post before figuring out the answer.
This code manually copies whatever the user currently has selected to the OS buffer.
You could easily modify it to act differently on these different inputs.

 void OnGUI() {
 /*
     Your code for drawing fields goes here
 */
 var textEditor = EditorGUIUtility.GetStateObject(typeof(TextEditor), EditorGUIUtility.keyboardControl) as TextEditor;

 if (textEditor != null) {
     if (focusedWindow == this) {
         // shift + x
         if (Event.current.Equals(Event.KeyboardEvent("#x")))
             textEditor.Cut();
         // shift + c
         if (Event.current.Equals(Event.KeyboardEvent("#c")))
             textEditor.Copy();
         // shift + v
         if (Event.current.Equals(Event.KeyboardEvent("#v")))
             textEditor.Paste();
     }
 }
 }

This post got me on track:
http://forum.unity3d.com/threads/copy-textfield-or-textarea-text-to-clipboard.24101/#post-813226 This piece of documentation described how to get the keyboard input: http://docs.unity3d.com/ScriptReference/Event.KeyboardEvent.html

Unfortunately, the command for ctrl+c, "^c" , etc. are suppressed, probably by the inputfield, but I found that using shift as a substite, so "#c", did work, so that's how I left it.