title: Undoing diff put when copying lines between vimdiff windows
body: <p>If, at a command prompt, I run</p>
  
  <pre><code>vimdiff file1 file2
  </code></pre>
  
  <p>I get a vim instance that has two files open side-by-side. Let's suppose that the text in the files looks like this (file1 is on the left, file2 on the right):</p>
  
  <pre><code>╔═══════╤═══════╗
  ║foo    │-------║
  ║bar    │bar    ║
  ║grue   │-------║
  ║~      │~      ║
  ║~      │~      ║
  ╚═══════╧═══════╝
  </code></pre>
  
  <p>Now suppose that my cursor is on the "f" of "foo" and that I wish to copy the first line of file1 to the first line of file2.</p>
  
  <p>One way to do this is to select and yank (copy) the line with <strong>v$ y</strong>, and then use <strong>Ctrl+w l</strong> to move the cursor across to the first line of file2, and then type <strong>p</strong> to paste the copied line. If I do this and I then decide I didn't really want to do it after all, I can press <strong>u</strong> to undo the paste command I carried out in file2.</p>
  
  <p>Another way to do it is to use the diff put command dp. However, if after doing this I decide I didn't mean to do it, I can't undo it simply by pressing <strong>u</strong> because my cursor is still in file1 and the <strong>u</strong> command will undo the most recent change to file1, <em>not</em> the most recent change to file2. So instead I have to use <strong>Ctrl+w l</strong> or <strong>Ctrl+w w</strong> to move the cursor to the window for file2 and <em>then</em> press <strong>u</strong>.</p>
  
  <p>So, my question is: after I have used <strong>dp</strong> as above, is there any easy way for me to undo it without having to move my cursor across to the other file's window?</p>