I hesitate to disagrees with Mr. JohnBuckner as he is most often correct. Now, while mass balancing is a big aid in many cases, it rarely corrects a flutter problem but does help in many other ways. Flutter is when a surface continues in oscillation once energized by some external force and a mass balance can remove some of this external stimulation. However, it has not changed the resonant frequency of the surface so, if it gets stimulated by some other force like wimpy push rods, sloppy hinges etc. it will still flutter. The ideal surface that will never flutter is one that has zero mass and infinite stiffness (an unobtainable condition) but you strive for that by building the surface as light and stiff as you can and make sure you have very stiff control rods (or push-pull lines) and zero slop in all pivot points. On ailerons, you can often stop a flutter problem by laminating a very thin layer of material over the top of the existing surface. This makes it stiffer and also, if the leading edge of the aileron is slightly thicker than the trailing edge of the wing surface it is mounted to, you remove a lot of the stimulus that caused flutter in the first place.