gridview row on mouse over popup image?

You can do the following by:
1. Inject Javascript function on mousehover & mouseout of the link in a grid row.
2. Using JavaScript, show a div that contains the needed details(image here) when you hover your mouseover that row
3. Using JavaScript, hide the div onmouseout.


For injecting JS, you need to use RowDataBound of GridView, something like:

protected void GridView_RowDataBound(Object sender, GridViewRowEventArgs e)
{  
   DataControlRowType rtype = e.Row.RowType;   
   if (rtype == DataControlRowType.DataRow && rtype != DataControlRowType.Footer 
       && rtype != DataControlRowType.Separator && rtype != DataControlRowType.Header 
       && rtype != DataControlRowType.Pager)   
   {  
      // Show div    
      // Add parameters of image as per need. may be image location passed
      e.Row.Attributes.Add("onmouseover", "ShowDiv(this);");
      //Hide div
      e.Row.Attributes.Add("onmouseover", "HideDiv(this);");
   }
}

Show the div onmouseover event of the grid cell, and
Hide the div onmoustout event of the grid cell.

Try!