title: How to right button drag with Win32 API?
body: <p>I implemented the IDropTarget interface and the drag &amp; drop (file from explorer) works well.</p>
  
  <p>When I drag &amp; drop a file with right mouse button, the context menu does not popup.</p>
  
  <p>So I think it's my responsibility to show the context menu,</p>
  
  <p>But in IDropTarget::Drop method, (grfKeyState &amp; MK_RBUTTON) is always 0.</p>
  
  <p>How can I know if the drag mouse button was right?</p>
  
  <p>And is there a special method to show menu and receive the selection after the drop?</p>
  
  <p>(I prefer the Win32 API way, I don't use MFC.)</p>