Extending ContentBySearchWebPart with own buttons

Question

Dear all,
I want to extend the Content Search Web Part (CSWB) with own buttons/tabs to refine the query. My idea was to derive a custom web part from the CSWB, add these buttons to the web part area and to extend the query in the button's event.
My actual problem is to place the button to the web part area. I used the CreateChildControls() method to add my buttons (to be exact RadioButton) to the Controls collection, but the buttons will be always attached at the bottom of the web part.
Here is my code:
protected override void CreateChildControls()
base.CreateChildControls();
//create filter buttons
for (int i = 0; i < 3; i++)
var filter = new RadioButton();
filter.Text = "filter " + i.ToString();
filter.GroupName = "NewsCSWP_tabs";
//set input properties
filter.InputAttributes["class"] = "NewsCSWP_radio";
//this.Controls.Add(filter);
this.Controls.AddAt(0, filter);
And it has the same effect if I use the .Add(...) or .AddAt(...) method. I tried also to call the base.CreateChildControls() after the Controls.Add(), but my buttons still appears at the bottom.
What is the supported way to achive this?
Thanks!

Answer 1

Maybe its  possible, but it is not recommended to do so.
However it does not make to much sense.
Just run your servlet as a portal compoent with an entry as native-Servlet in the pc descriptor.
Thats a 5 minute trip.