You just need
Opt("MouseCoordMode", 0) ;1=absolute, 0=relative, 2=client
This will make your clicks relative to the window you are working with.
Use window info Tool to find those coordinates. Go to options and set Coord mode to Window.
You can also use
ControlClick ( "title", "text", controlID [, button [, clicks [, x [, y]]]] )
Any of these two methods are not dependant on your screen resolution.