EventType.ValidateCommand

Validates a special command (e.g. copy & paste)

"Copy", "Cut", "Paste", "Delete", "FrameSelected", "Duplicate", "SelectAll" and so on. Sent only in the editor.

Example: Make pasting work in current window or control:

function OnGUI()
{
var e:Event = Event.current;

if (e.type == EventType.ValidateCommand && e.commandName == "Paste")
{
Debug.Log("validate paste");
e.Use(); // without this line we won't get ExecuteCommand
}

if (e.type == EventType.ExecuteCommand && e.commandName == "Paste")
{
Debug.Log("Pasting: " + EditorGUIUtility.systemCopyBuffer);
}
}