Update Panel(Ajax)Question

Good Morning All

I have a user control that i have exposed selection of the items through a hiden texbox and it working fine that way. and i have grouped Controls(not a usercontrol)All this are inside an Update Panel. Now in the group controls i have a gridview. Now as i said ontextchange event of the usercontrol i want to update the display on the Gridview and the page must not flicker. i have Attached the Screenshot of my Page. The Left part is usercontrol and the right part is not the usercontrol and at the bottom i have highlisted the textbox that changes when the items are selected. and there is a grid on the right, that i was to update when the text changes from the textbox at the bottom


Thank you