IndexOfSelectable
int32 index = IndexOfSelectable(fSelection->SelectableAtFast(i));
virtual int32 IndexOfSelectable(Selectable* selectable) const;
virtual int32 IndexOfSelectable(Selectable* selectable) const;
virtual int32 IndexOfSelectable(Selectable* selectable) const;
virtual int32 IndexOfSelectable(Selectable* selectable) const;
virtual int32 IndexOfSelectable(Selectable* selectable) const;