I am creating a custom ASP.NET textbox control and I am trying to set the default CssClass, but I can't figure out how.
I have added attributes to the controls (OnBlur and OnFocus) those work fine changing the cssClass, but when the page initially loads the textbox doesn't have a default cssClass.

Here's my code
VB Code:
  1. Imports System

  2. Imports System.Web

  3. Imports System.Web.UI

  4. Imports System.Web.UI.WebControls

  5. Imports System.ComponentModel

  6.  
  7. Namespace JHATextBox

  8.  
  9.     Public Class JHATextBox

  10.         Inherits TextBox

  11.  
  12.         'This should be the default cssClass when the page loads.

  13.         Private _cssClass As String = "formBox"

  14.  
  15.         Protected Overrides Sub Render(ByVal writer As HtmlTextWriter)

  16.             Dim strScript As String = ""

  17.  
  18.             If Page.IsClientScriptBlockRegistered("ClientScript") = False Then

  19.                 strScript &= "<script language=""javascript"" type=""text/javascript"">" & vbCrLf

  20.                 strScript &= vbTab & "function activeField(ptr){" & vbCrLf

  21.                 strScript &= vbTab & vbTab & "if((ptr.disabled != true) && (ptr.readOnly != true)) {" & vbCrLf

  22.                 strScript &= vbTab & vbTab & vbTab & "ptr.className = 'formBoxSelected';" & vbCrLf

  23.                 strScript &= vbTab & vbTab & "}" & vbCrLf

  24.                 strScript &= vbTab & "}" & vbCrLf

  25.                 strScript &= vbTab & "function inactiveField(ptr) {" & vbCrLf

  26.                 strScript &= vbTab & vbTab & "if((ptr.disabled != true) && (ptr.readOnly != true)) {" & vbCrLf

  27.                 strScript &= vbTab & vbTab & vbTab & "ptr.className = 'formBox';" & vbCrLf

  28.                 strScript &= vbTab & vbTab & "}" & vbCrLf

  29.                 strScript &= vbTab & "}" & vbCrLf

  30.                 strScript &= "</script>" & vbCrLf

  31.  
  32.                 Page.RegisterStartupScript("ClientScript", strScript)

  33.             End If

  34.  
  35.             writer.AddAttribute("onBlur", "void inactiveField(this);")

  36.             writer.AddAttribute("onFocus", "void activeField(this);")

  37.             writer.RenderBeginTag("input")

  38.             writer.RenderEndTag()

  39.  
  40.         End Sub

  41.  
  42.         Public Overrides Property CssClass() As String

  43.             Get

  44.                 Return _cssClass

  45.             End Get

  46.             Set(ByVal Value As String)

  47.                 _cssClass = Value

  48.             End Set

  49.         End Property

  50.  
  51.     End Class

  52.  
  53. End Namespace
If I just type formBox as the CssClass into the controls properties, it works fine, but I can't set it in the code above for some reason.