How can I hide the gridview once an item is selected from the dropdownlist? It is not visible when the page loads initially but once a selection is made it stays visible while the loading .gif is displayed. I want to hide it while the .gif is displayed.
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager><asp:UpdatePanel ID="UpdatePanel1" runat="server"><ContentTemplate><div><table class="style1"><tr><td class="style2"></td><td class="style3"> </td><td> </td></tr><tr><td class="style2"><asp:Label ID="Label1" runat="server" Text="Schedule Slot:" Font-Bold="True"
ForeColor="White"></asp:Label> <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"
BackColor="White" DataSourceID="SqlDataSource1" DataTextField="slot"
DataValueField="slot" ForeColor="Black"></asp:DropDownList> </td><td class="style3"> </td><td><asp:UpdateProgress ID="UpdateProgress1" runat="server"
AssociatedUpdatePanelID="UpdatePanel1"><ProgressTemplate><img alt="checking" src="/processing.gif" style="height: 38px; width: 144px" /> </ProgressTemplate></asp:UpdateProgress><asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
BorderStyle="None" DataSourceID="SqlDataSource2" Font-Bold="True"
ForeColor="White" GridLines="None"><Columns><asp:BoundField DataField="Column1" HeaderText="Next Available Slot"
NullDisplayText="No Slots Available" ReadOnly="True" ShowHeader="False"
SortExpression="Column1"><HeaderStyle Font-Underline="True" /></asp:BoundField></Columns></asp:GridView></td></tr><tr><td class="style2"> </td><td class="style3"> </td><td> </td></tr></table></div></ContentTemplate></asp:UpdatePanel>