Gridlayout mode simply means that all controls will be positioned using
Cascading Style Sheet level II (absolute positioning). To get a DataGrid
and a Textbox to move together, you should put them both inside a <DIV> tag
and then position the DIV tag, rather than the grid or textbox.
You can accomplish this by putting a FlowLayout Panel control on your page
(that is in GridLayout mode) and put the grid and the textbox in the panel.