Content jumps around on inserting or updating TextBoxes/DropDownList

Question

My .aspx form dances around when I tab from a textBox to another textBox, but the worst jumping around occurs when I tab to or from a DropDownList.

All I have is few textboxes. nothing complex, no gridviews, no labels.

What am I doing wrong?

IE8 .NET 3.5

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="Requestor.aspx.vb" Inherits="RCCRSAdmin.Requestor" MasterPageFile="~/RCCRS.Master" %> <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>

Requestor Centre Username --%> User Type Staff No --%> Password Forename Surname Email Mobile Tel Office        

Answer 1

Without any examples to look at it's difficult to say but here are some things to look out for that can cause browser reflow.

1. The CSS pseudo-class :focus might be defining an alternate border or margin width.

2. OnFocus/onBlur events on elements that trigger JavaScript to alter the DOM.

Answer 2

Not sure what you mean by "dance around". Is this a tab index issue? In which case, the TabIndex attribute on the element should help.