which notification (message) tells us if the user changes screen resolution ?
Probably WM_SETTINGCHANGE though I'm not sure if resolution is covered by that one.
All top-level windows receive WM_SETTINGSCHANGE when any of the SystemParametersInfo values changes.
While it doesn't strictly give the screen resolution, SPI_GETWORKAREA gives the usable desktop area which should be what you're actually interested in.
WM_SETTINGCHANGE -- http://msdn.microsoft.com/en-us/library/ms725497%28v=VS.85%29.aspx
SystemParametersInfo -- http://msdn.microsoft.com/en-us/library/ms724947%28VS.85%29.aspx
thanks guys
i found it...
WM_DISPLAYCHANGE
i made my program display the message values, then changed resolution and went through the list :P