title: how to set primary monitor for Windows-7, in C#
body: <p>I believe I will need an example of doing this in SetDisplayConfig().</p>
  
  <p>My Windows-7 system has two monitors.  When my program is in one mode, the 1st monitor must be on and primary, and the 2nd monitor off.  In the other mode, vice versa:  1st monitor off, 2nd monitor on and primary.</p>
  
  <p>I've searched and searched for how to do it with Windows SDK function "SetDisplayConfig()" but found nothing.  The MSDN reference to SetDisplayConfig() is too esoteric for me, and has no example code.</p>
  
  <p>I got it going using ChangeDisplaySettingsEx(), but this function is flaky in Windows-7.</p>
  
  <p>Thanks!</p>