There are only a handful of Toolkit controls with the same name as standard asp.net webcontrol and I find I rarely have conflicts. If I do it's simple to prefix namespace one or the other. And, it's only an issue with the server-side code.
You can also alias the objects as the following sample demonstrates.
Example
using System;
using Coolite.Ext.Web;
using Button = Coolite.Ext.Web.Button;
using Panel = Coolite.Ext.Web.Panel;
namespace Coolite.Sandbox.Temp.Window
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Button button = new Button();
Panel panel = new Panel();
System.Web.UI.WebControls.Panel panel2 = new System.Web.UI.WebControls.Panel();
}
}
}
And, it's never a problem if you don't import the System.Web.UI.WebControls namespace. ;)
Hope this helps.