Are you looking for something like this? I couldn't figure out how to make the tool tip work correctly with the graphics primitive so I just used a ListPlot instead. You should be able to play around with this and get what you want. There's probably a way to do it with the Point graphics primitive, but couldn't figure out off hand.
Also... I get a lot of my tough questions answered on stackoverflow.com, formally stackexchange.com. They have a mathematica forum that's awesome. I started using it a couple months ago and I'm stoked. I find that my questions get answered quick, and there's people moderating to make sure everything is organized. Hope this helps. I like the wolfram community too... but in my experience its not quite as helpful. I still jump on here sometimes though. Good luck!
Manipulate[L = Length@datafreqt;
mm = MovingAverage[datafreqt[[Range[a, b]]], m];
If[L - 1 > a >= b, b = a + 1];
If[a === L, a = L - 1; b = L];
If[m > b - a, m = b - a];
Pane[Show[
ListPlot[Tooltip[Transpose[{Range@L, datafreqt}]],
PlotStyle -> PointSize[.01]],
Graphics[{
Thin, GrayLevel[.5], Line@Transpose[{Range@L, datafreqt}],
Thick, Red,
Line@Transpose[{Range[a, b, (b - a)/(Length[mm] - 1)], mm}]},
PlotLabel -> Style["Test with TOOLTIP", "Title", 12],
BaseStyle -> {FontFamily -> "Arial", FontWeight -> "Bold",
FontSize -> 11}, Frame -> True,
FrameLabel -> {"Test [%]", "Test [n]"}, GridLines -> Automatic,
GridLinesStyle -> Directive[Black, Dotted],
PlotRange -> {{0, 101}, {0, 200}}, AspectRatio -> .5,
Axes -> True, Ticks -> {None, Automatic}], PlotRange -> {0, 200}],
ImageSize -> 350], {{m, 1, "m\[Hyphen]day moving average"}, 1,
Max[b - a, 1], 1,
Appearance -> "Labeled"}, "time span:", {{a, Floor[.25 L],
"lower limit"}, 1, L, 1,
Appearance -> "Labeled"}, {{b, Floor[.75 L], "upper limit"}, 1, L,
1, Appearance -> "Labeled"}, SaveDefinitions -> True,
TrackedSymbols -> True]