Change backColor of Repeater Button onClick

Question

I have Repeater buttons that i want to change their backcolor on click. The problem is that I dont know how to identify which button is clicked and I cant reach it through the onclick function. Just to make it clear - I want to change the button that has been clicked. It should be like a "selected" button.

THOSE ARE THE BUTTONS

<asp:Repeater ID="rptFillButtonCategory" runat="server">
    <ItemTemplate>
        <asp:Button ID="FillButton" runat="server" Width="100%" OnClick="ButtonSelectionFill" 
             CommandArgument='<%#DataBinder.Eval(Container.DataItem, "Id") %>' 
             Text='<%#DataBinder.Eval(Container.DataItem, "Name") + " for next version" %>'/>
    </ItemTemplate>
</asp:Repeater>

This is the on click function

public void ButtonSelectionFill(object o, EventArgs e)
{
    Button btn = ((Button)o);
    btn.BackColor = System.Drawing.Color.Red;
    DropCategory.SelectedValue = Convert.ToInt16(((Button)o).CommandArgument.ToString());
}

Thank you for the help.

Answer 1

This worked:

<asp:Repeater ID="Repeater1" runat="server" DataSourceID="ObjectDataSource1">
    <ItemTemplate>
        <asp:Button ID="Button1" runat="server" 
            Text='<%#DataBinder.Eval(Container.DataItem, "Id") %>' OnClick="Button1_Click" />
    </ItemTemplate>
</asp:Repeater>

protected void Button1_Click(object sender, EventArgs e)
{
    Button b = (Button)sender;
    b.BackColor = System.Drawing.Color.Red;
}