I did a quick search on Google groups - it seems that this is discussed several times (and several products are beeing mentioned...).
One method is to provide a 'mirror driver' to intercept the all calls from GDI to the display driver (this should be the method used by Netmeeting). There should be a sample in the windows DDK in %WINDDK% \src\video\displays\mirror\disp\. The link is http://www.microsoft.com/hwdev/tech/display/default.asp. As the windwos sample code probably is limited by some licensing issues the driver probably has to be developed without this code - but IANAL. Med venlig hilsen / Regards Franz Wolfhagen
