protected void Page_Load(object sender, EventArgs e)
    {
        RadGrid1.HeaderContextMenu.ClickToOpen = true;
    }

<script>
    var original = Telerik.Web.UI.GridColumn.prototype._onContextMenuItemClicking;
    Telerik.Web.UI.GridColumn.prototype._onContextMenuItemClicking = function (sender, args) {
        original.call(this, sender, args);
                
        var item = args.get_item();
        var itemValue = item.get_value();
        if (itemValue == "FilterList" || itemValue == "FilterMenuContainer" ||
            itemValue == "AggregatesContainer" || itemValue == "FilterMenuParent" || itemValue == "ColumnsContainer" ||
            (Telerik.Web.UI.RadMenuItem.isInstanceOfType(item.get_parent()) && item.get_parent().get_value() == "ColumnsContainer")) {
            if (sender.get_clickToOpen()) {
                args.get_item().open();
            }
        }
    }
</script>

When using iPad touch to open the header context menu of a grid column, an immediate postback prevents the opening of the menu when the RadGrid is in Mobile RenderMode. The reason is that this action gets recognized as dragging when AllowDragToGroup is enabled.

<telerik:RadGrid ID="RGTimesheet" runat="server" OnNeedDataSource="RGTimesheet_NeedDataSource" RenderMode="Mobile"
    AllowAutomaticInserts="True" AllowAutomaticUpdates="True" AllowAutomaticDeletes="True"
    Skin="MetroTouch"
    Width="100%" AllowSorting="True" GroupPanelPosition="Top">
    <ClientSettings>
        <Scrolling AllowScroll="True" UseStaticHeaders="True"></Scrolling>
    </ClientSettings>
    <MasterTableView AutoGenerateColumns="False" CommandItemDisplay="Bottom" DataKeyNames="OrderID" ShowFooter="True">
        <Columns>
            <telerik:GridEditCommandColumn ButtonType="FontIconButton">
            </telerik:GridEditCommandColumn>
            <telerik:GridClientDeleteColumn ButtonType="FontIconButton">
            </telerik:GridClientDeleteColumn>

            <telerik:GridDateTimeColumn DataField="Start" DataType="System.TimeSpan" EditDataFormatString="hh:mm:ss tt" HeaderText="Start" SortExpression="Start" UniqueName="Start" PickerType="TimePicker">
            </telerik:GridDateTimeColumn>
            <telerik:GridDateTimeColumn DataField="Finish" DataType="System.TimeSpan" HeaderText="Finish" SortExpression="Finish" UniqueName="Finish" PickerType="TimePicker">
            </telerik:GridDateTimeColumn>

        </Columns>
        <EditFormSettings>
            <EditColumn UniqueName="EditCommandColumn1" ButtonType="PushButton">
            </EditColumn>
        </EditFormSettings>
    </MasterTableView>
</telerik:RadGrid>

private DataTable OrdersTable()
{
    DataTable dt = new DataTable();

    dt.Columns.Add(new DataColumn("OrderID", typeof(int)));
    dt.Columns.Add(new DataColumn("Start", typeof(TimeSpan)));
    dt.Columns.Add(new DataColumn("Finish", typeof(TimeSpan)));

    dt.PrimaryKey = new DataColumn[] { dt.Columns["OrderID"] };

    for (int i = 0; i < 10; i++)
    {
        int index = i + 1;

        DataRow row = dt.NewRow();

        int hours = DateTime.Now.Hour;
        int minutes = DateTime.Now.Minute;
        int seconds = DateTime.Now.Second;

        row["OrderID"] = index;
        row["Start"] = new TimeSpan(hours, minutes, seconds);
        row["Finish"] = new TimeSpan(hours+index, minutes, seconds);

        dt.Rows.Add(row);
    }

    return dt;
}


protected void RGTimesheet_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
    RGTimesheet.DataSource = OrdersTable();
}

<ClientSettings AllowRowsDragDrop="true">
    <Selecting AllowRowSelect="true" />
    <ClientEvents OnRowDropping="function() {alert('RowDrooping event fired!');}"/>
</ClientSettings>

<telerik:RadButton runat="server" ID="RadButton1" Text="Hide Grids with no Contrast issues" AutoPostBack="false" OnClientClicked="OnClientClicked" />
<script>
    function OnClientClicked(sender, args) {
        var $ = $ || $telerik.$;
        var failingSkins = []
        $(".RadGrid").each(function () {
            var grid = $(this)
            if (grid.find(".ANDI508-element-danger").length == 0) {
                grid.parent().hide();
            } else {
                failingSkins.push(grid.parent().find(".label").text())
            }
        })
        console.log(failingSkins)
    }
</script>

<a href="javascript:void((function(){andiScript=document.createElement('script');andiScript.setAttribute('src','https://www.ssa.gov/accessibility/andi/andi.js');document.body.appendChild(andiScript)})());">Run ANDI tool</a>
<br />
<telerik:RadSkinManager ID="RadSkinManager1" runat="server"></telerik:RadSkinManager>
<asp:Repeater runat="server" ID="Repeater1" OnItemDataBound="Repeater1_ItemDataBound">
    <SeparatorTemplate>
        <hr />
    </SeparatorTemplate>
    <ItemTemplate>
        <div class="container">
            <asp:Label Text="Label1" CssClass="label" ID="Label1" runat="server" />
            <telerik:RadGrid ID="RadGrid1" RenderMode="Lightweight" runat="server" AllowPaging="True" CellSpacing="0"
                GridLines="None" Width="800px" PageSize="10" OnNeedDataSource="RadGrid1_NeedDataSource"
                AllowSorting="true">
                <MasterTableView AutoGenerateColumns="False" DataKeyNames="OrderID">
                    <Columns>
                        <telerik:GridHyperLinkColumn DataTextField="ShipName" DataNavigateUrlFields="OrderID" DataNavigateUrlFormatString="https://google.com/search?q={0}" Target="_blank"></telerik:GridHyperLinkColumn>
                    </Columns>
                </MasterTableView>
            </telerik:RadGrid>

        </div>

    </ItemTemplate>
</asp:Repeater>

protected void Page_Load(object sender, EventArgs e)
{
    Repeater1.DataSource = RadSkinManager1.GetSkinChooser().Items;
    Repeater1.DataBind();
}
protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
    (sender as RadGrid).DataSource = Enumerable.Range(1,70).Select(x=> new { OrderID = x, ShipName = "Ship name #" + x });
}

protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    var grid = e.Item.FindControl("RadGrid1") as RadGrid;
    if (grid != null)
    {
        var skin = (e.Item.DataItem as RadComboBoxItem).Text;
        grid.Skin = skin;
        (e.Item.FindControl("Label1") as Label).Text=skin;

    }
}

<telerik:RadAjaxPanel runat="server" ID="panel" LoadingPanelID="RadAjaxLoadingPanel1" RenderMode="Inline" EnableAJAX="true">
    <div class="row">
        <asp:Button runat="server" ID="btnLoad" Text="Load Data" OnClick="btnLoad_Click" />
    </div>

    <telerik:RadGrid runat="server" ID="radGrid" CssClass="radgrid" Skin="Bootstrap"
        ClientSettings-Scrolling-AllowScroll="true"
        ClientSettings-Scrolling-ScrollHeight="800"
        ClientSettings-Scrolling-UseStaticHeaders="true"
        ClientSettings-EnableAlternatingItems="false"
        HeaderStyle-Wrap="false" AllowPaging="true" PageSize="50"
        ItemStyle-Wrap="false" AllowSorting="true"
        OnNeedDataSource="radGrid_NeedDataSource" AllowMultiRowSelection="false"
        HeaderStyle-BackColor="White">
        <ClientSettings>
            <Selecting AllowRowSelect="true" />

        </ClientSettings>
        <MasterTableView>
            <Columns>
                <telerik:GridTemplateColumn UniqueName="colEdit" AllowFiltering="false" Exportable="false">
                    <ItemTemplate>
                        <asp:LinkButton CssClass="link-button" runat="server" ID="btnEdit">Edit</asp:LinkButton>
                    </ItemTemplate>
                </telerik:GridTemplateColumn>
                <telerik:GridTemplateColumn UniqueName="colDelete" AllowFiltering="false" Exportable="false">
                    <ItemTemplate>
                        <asp:LinkButton CssClass="link-button" ID="btnDelete" runat="server">Delete</asp:LinkButton>
                    </ItemTemplate>
                </telerik:GridTemplateColumn>
            </Columns>
        </MasterTableView>
    </telerik:RadGrid>

</telerik:RadAjaxPanel>

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        radGrid.Visible = false;
    }
}

protected void btnLoad_Click(object sender, EventArgs e)
{
    radGrid.Visible = true;
    radGrid.Rebind();
}
protected void radGrid_NeedDataSource(object sender, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
{
    var grid = sender as RadGrid;
    grid.DataSource = LoadData();
}
private DataTable LoadData()
{
    DataTable tbl = new DataTable();
    tbl.Columns.Add(new DataColumn("ADFAFD", typeof(string)));
    tbl.Columns.Add(new DataColumn("ADFADFADF", typeof(string)));
    tbl.Columns.Add(new DataColumn("ADFADFADFADFASDF", typeof(string)));
    tbl.Columns.Add(new DataColumn("HGDH", typeof(string)));
    tbl.Columns.Add(new DataColumn("ADFADF ADFADFADF", typeof(string)));
    tbl.Columns.Add(new DataColumn("ADF ADSFADF", typeof(string)));
    tbl.Columns.Add(new DataColumn("FKHDGJHFGJH", typeof(string)));
    tbl.Columns.Add(new DataColumn("SHFSFHSGH", typeof(string)));
    tbl.Columns.Add(new DataColumn("ADF ASDFASDF ASDFADSF", typeof(string)));
    tbl.Rows.Add(new object[] { "ADFADF", "ASDFADFAFD", "ADFADF", "ADFADFADF ADFADFADFADF ADFADF ADFADFADF ADFADFADFADF ADFADF", "ADFADF", "ASDFADFAFD", "ADFADF", "ADFADFADF ADFADFADFADF ADFADF"});
    tbl.Rows.Add(new object[] { "ADFADF", "ASDFADFAFD", "ADFADF", "ADFADFADF ADFADFADFADF ADFADF", "ADFADF", "ASDFADFAFD", "ADFADF", "ADFADFADF ADFADFADFADF ADFADF"});
    return tbl;
}

<ExportSettings>
    <Excel Format="Biff"  DefaultCellAlignment="NotSet"/>
</ExportSettings>

protected void Page_Init(object sender, System.EventArgs e)
{
    var culture = new System.Globalization.CultureInfo("fa-IR");

    System.Threading.Thread.CurrentThread.CurrentCulture = culture;
    System.Threading.Thread.CurrentThread.CurrentUICulture = culture;
}

<telerik:RadGrid ID="RadGrid1" runat="server" RenderMode="Lightweight">
</telerik:RadGrid>