Improve the use of HiddenField inputs' values.

When using RadAjaxManager or RadAjaxPanel in SharePoint 2019 for the purpose to enable ajax for Controls, a partial PostBack will cause the page become Blank. A test was conducted using the generic ASP UpdatePanel which worked as expected.

For the time being the property can be set on the client through the chartObject. For example:
JavaScript:
	<script>
		function pageLoad() {
			var chart = $find("<%=RadHtmlChart1.ClientID%>");
			chart._chartObject.options.series[0].highlight = {
				markers: {
					visible: true
				}
			}
			chart.repaint();
		}
	</script>
ASPX:
		<telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" Width="600" Height="400">
			<PlotArea>
				<Series>
					<telerik:LineSeries>
						<MarkersAppearance Visible="false" />
						<SeriesItems>
							<telerik:CategorySeriesItem Y="30" />
							<telerik:CategorySeriesItem Y="10" />
							<telerik:CategorySeriesItem Y="20" />
							<telerik:CategorySeriesItem Y="15" />
						</SeriesItems>
					</telerik:LineSeries>
				</Series>
			</PlotArea>
		</telerik:RadHtmlChart>

The functionality is currently exposed only by the x-axis of the sparkliens. It would be a good idea to be exposed by the other series types as well.

For the time being you can configure the cross hair through the kendo widget:
<script>
			function pageLoad() {
				$find('RadHtmlChart1').get_kendoWidget().setOptions({categoryAxis:{crosshair:{ color: "green", width: 2, visible: true}}});
			}
		</script>
		<telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" Width="600" Height="400">
			<PlotArea>
				<Series>
					<telerik:ColumnSeries Name="Series 1">
						<SeriesItems>
							<telerik:CategorySeriesItem Y="30" />
							<telerik:CategorySeriesItem Y="10" />
							<telerik:CategorySeriesItem Y="20" />
						</SeriesItems>
					</telerik:ColumnSeries>
					<telerik:LineSeries Name="Series 2">
						<SeriesItems>
							<telerik:CategorySeriesItem Y="39" />
							<telerik:CategorySeriesItem Y="19" />
							<telerik:CategorySeriesItem Y="29" />
						</SeriesItems>
					</telerik:LineSeries>
				</Series>
				<XAxis>
					<LabelsAppearance RotationAngle="33"></LabelsAppearance>
					<Items>
						<telerik:AxisItem LabelText="Item 1" />
						<telerik:AxisItem LabelText="Item 2" />
						<telerik:AxisItem LabelText="Item 3" />
					</Items>
				</XAxis>
			</PlotArea>
		</telerik:RadHtmlChart>

For the time being you can use the following workaround:
		<script>
			function OnLoad(sender, args) {
				var kendoWidget = $find('<%=RadHtmlChart1.ClientID%>').get_kendoWidget();
				kendoWidget.options.legend.reverse = true;
				kendoWidget.redraw();
			}
		</script>
		<telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" Width="600" Height="400">
			<ClientEvents OnLoad="OnLoad" />
			<PlotArea>
				<Series>
					<telerik:ColumnSeries Name="Series 1">
						<SeriesItems>
							<telerik:CategorySeriesItem Y="30" />
							<telerik:CategorySeriesItem Y="10" />
							<telerik:CategorySeriesItem Y="20" />
						</SeriesItems>
					</telerik:ColumnSeries>
					<telerik:ColumnSeries Name="Series 2">
						<SeriesItems>
							<telerik:CategorySeriesItem Y="2" />
							<telerik:CategorySeriesItem Y="5" />
							<telerik:CategorySeriesItem Y="7" />
						</SeriesItems>
					</telerik:ColumnSeries>
					<telerik:ColumnSeries Name="Series 3">
						<SeriesItems>
							<telerik:CategorySeriesItem Y="9" />
							<telerik:CategorySeriesItem Y="11" />
							<telerik:CategorySeriesItem Y="13" />
						</SeriesItems>
					</telerik:ColumnSeries>
				</Series>
				<XAxis>
					<LabelsAppearance RotationAngle="33"></LabelsAppearance>
					<Items>
						<telerik:AxisItem LabelText="Item 1" />
						<telerik:AxisItem LabelText="Item 2" />
						<telerik:AxisItem LabelText="Item 3" />
					</Items>
				</XAxis>
			</PlotArea>
		</telerik:RadHtmlChart>

Currenlty Series like Bubble, Bar, Column, Donut, Pie and Candlestick do not expose any appearance properties for the Series border. Expose appearance border properties like width, dashtype, color and opacity.

Temporary workaround for managing the border appearance:
Javascript:
	<script language="javascript">
		function pageLoad() {
			var chart = $find("RadHtmlChart1");
			chart._chartObject.options.series[0].border = {
				width: 2,
				color: "black",
				dashType: "dash",
				opacity: 0.2
			}
			chart.repaint();
		}
	</script>

ASPX:
	<telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" Width="600" Height="400">
		<PlotArea>
			<Series>
				<telerik:ColumnSeries>
					<SeriesItems>
						<telerik:CategorySeriesItem Y="30" />
						<telerik:CategorySeriesItem Y="10" />
						<telerik:CategorySeriesItem Y="20" />
					</SeriesItems>
				</telerik:ColumnSeries>
			</Series>
		</PlotArea>
	</telerik:RadHtmlChart>

Currently the available appearance options of the line in Area, Line and ScatterLine Series are width and background color. Expose additional option for changing the dash type(e.g. dash, dashDot, Dot, etc). For the time being the following workaround can be used:
		<script>
			function pageLoad() {
				var chart = $find("<%=RadHtmlChart1.ClientID%>");
				//DashType: dash, dashDot, dot, longDash, longDashDot, longDashDotDot, solid
				chart._chartObject.options.series[0].dashType = "dot";
				chart.repaint();
			}
		</script>
		<telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" Width="600px" Height="400px">
			<PlotArea>
				<Series>
					<telerik:LineSeries Name="Series 1">
						<SeriesItems>
							<telerik:CategorySeriesItem Y="30" />
							<telerik:CategorySeriesItem Y="10" />
							<telerik:CategorySeriesItem Y="20" />
						</SeriesItems>
					</telerik:LineSeries>
				</Series>
				<XAxis>
					<Items>
						<telerik:AxisItem LabelText="item 1" />
						<telerik:AxisItem LabelText="item 2" />
						<telerik:AxisItem LabelText="item 3" />
					</Items>
				</XAxis>
			</PlotArea>
		</telerik:RadHtmlChart>