i recently removed a new vinyl window which had been installed with the top screws in the outer sash track and one screw in the middle of the top as well. the sill capping of this window was tucked in the groove of the window and not against the wood sill itself. this eliminated the need for a sill extender that is typically used. i myself find issues with these two techniques. however i would better my side of the coming argument by some more professional input. the screws i removed were not predrilled so that the threads would not allow any sort of movement of the frame. does either or both of these techniques void the warranty. any sort of input would be appreciated.