How to know whether Ctrl, Alt… keys are down

Use GetKeyState.  If higher order bit of return value is 1 ie if return value is 0x8000 then the key is down. (0x8000 is equivalent to 1000 0000 0000 0000 )

[sourcecode language=’cpp’]bool IsCtrlPressed()
{
      return ( GetKeyState( VK_CONTROL ) & 0x8000 ) == 0x8000 );
}

bool IsAltPressed()
{
     return ( GetKeyState( VK_MENU ) & 0x8000 ) == 0x8000 );
}[/sourcecode]

Appreciate your comments...