fns[x_] := {Log[x], Exp[x], Sin[x], Cos[x]};
len := Length[fns[x]];
DynamicModule[{pos = Table[{1, fns[1][[i]]}, {i, len}]},
LocatorPane[
Dynamic[pos, (pos = MapIndexed[{##} /. {{x_, y_}, {i_}} :> {x, fns[x][[i]]} &, #]) &],
Plot[Evaluate[fns[x]], {x, 0, 10}, PlotRange -> {-5, 5}],
Appearance ->
Table[Framed[Text@TraditionalForm[fns[x][[i]]], RoundingRadius -> 5,
Background -> White], {i, len}]]]