Width and height properties for the legend that will provide firm dimensions in pixels, so regardless of the series names' length, it will always have constant size.
You can set width and height through the kendo widget:
		<script>
			function pageLoad() {
				var chart = $find("<%=DonutChart.ClientID%>").get_kendoWidget();
				chart.options.legend.height = 80;
				chart.redraw();
			}
		</script>
		<telerik:RadHtmlChart runat="server" ID="DonutChart" Width="500" Height="500" Transitions="true">
			<Appearance>
				<FillStyle BackgroundColor="White"></FillStyle>
			</Appearance>
			<ChartTitle Text="OS Usage Statistics for December 2012">
				<Appearance Align="Center" Position="Top"></Appearance>
			</ChartTitle>
			<PlotArea>
				<Series>
					<telerik:DonutSeries>
						<LabelsAppearance Visible="false">
						</LabelsAppearance>
						<TooltipsAppearance DataFormatString="{0}%" BackgroundColor="White"></TooltipsAppearance>
						<SeriesItems>
							<telerik:PieSeriesItem BackgroundColor="#00adcc" Name="Win7"
								Y="55.6"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#cccccc" Name="Win8" Y="2.5"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#999999" Name="Vista" Y="2.8"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#888888" Name="NT" Y="1.8"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#777777" Name="WinXP" Y="21.1"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#666666" Name="Linux" Y="4.7"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#555555" Name="Mac" Y="8.7"></telerik:PieSeriesItem>
							<telerik:PieSeriesItem BackgroundColor="#444444" Name="Mobile" Y="2.2"></telerik:PieSeriesItem>
						</SeriesItems>
					</telerik:DonutSeries>
				</Series>
			</PlotArea>
		</telerik:RadHtmlChart>

Axes themselves do not have tooltips, only series do. Thus, tooltips cannot be added to the y-axis.
Add

Set tooltips of points between series points  - http://screencast.com/t/Q7FYJxkouLA

Tooltips of points between series points
See: http://screencast.com/t/Q7FYJxkouLA

In RadHtmlChart there is no property to specify Width for Bar/Column series. It automatically calculates series width based on chart width, number of series, number of items within series, gap and spacing, etc.,
If there is more than one bar/column chart in single page, there is no way to show Bar/Column series of exact width in all chart to make page consistent.

For the time begin the event logic can be executed with a small time out:

JavaScript

    <script type="text/javascript">
        var isFirstClick = "1";
        function OnClientSeriesClicked(sender, args) {
            setTimeout(function () {
                alert(isFirstClick);
            }, 0);
        }
    </script>
ASPX:

    <telerik:RadHtmlChart runat="server" Width="900px" Height="700px" ID="RadHtmlChart2"
        OnClientSeriesClicked="OnClientSeriesClicked">
        <PlotArea>
            <Series>
                <telerik:BarSeries>
                    <SeriesItems>
                        <telerik:CategorySeriesItem Y="10" />
                    </SeriesItems>
                </telerik:BarSeries>
            </Series>
        </PlotArea>
    </telerik:RadHtmlChart>

When you do a stacked HTMLChart (e.g. columns), the legend appears in the opposite order to the data series being stacked, which looks very unprofessional.

Hello,
Like a lot of companies we have multiple client side interfaces of a single application and have to create similar UI in multiple platforms.
For example I had to create a chart in both WPF and ASP.NET AJAX today.
The problem I have with the Telerik controls is that there are absolutely no standardization or consistency between platforms.
Why would a Cartesian Axis in WPF and ASP.NET AJAX and ASP MVC and Windows Universal Apps not all called the same thing?
It would be very simple to use interfaces to create some consistency between platforms.
Even better would be if Model Views are shared across platforms in a portable library: 
https://msdn.microsoft.com/en-us/library/hh563947(v=vs.110).aspx
https://msdn.microsoft.com/en-us/library/gg597391(v=vs.110).aspx
Regards,
Douw

The event should be similar to OnClientSeriesClicked event. It should expose information about the clicked series.

I would like to request a new feature in legend of RadHtmlChart that provide a tool-tip for long names because when I add a long text in legends the size of pie-chart is reduced. 
Sample code for what I expect to be working :

<telerik:RadHtmlChart runat="server" ID="Chart" Height="400px" Width="400px">
<ClientEvents OnLoad="onChartLoad" />
function onChartLoad()
{
var chart = $find("Chart");
var widget = chart.get_kendoWidget();
widget.options.legend.tooltip = "#: dataItem.columnname #" //Feature Request in this line
widget.redraw();
}

Allow the HTMLChart to be resized when the parent window is resized.
Currently the resize of the chart only occurs on page load or refresh only.

So i will resize the window and reload and the chart will fit into the space.

then if i enlarge the window the chart stays the current size.


This is particular important for us as our support of mobile devices (and responsive design)

the whole of our site is responsive apart from our charts :-( 

For the time being the following workaround can be used:

JavaScript:

    <script>
        function pageLoad() {
            var chart = $find("<%=RadHtmlChart1.ClientID%>");
            chart._chartObject.options.series[0].labels.background = "yellow";
            chart._chartObject.options.series[0].labels.border = {
                width: 2,
                dashType: "dashDot",
                color: "green"
            };
            chart.repaint();
        }
    </script>

ASPX:

        <telerik:RadHtmlChart ID="RadHtmlChart1" runat="server" Width="600" Height="400">
            <PlotArea>
                <Series>
                    <telerik:ColumnSeries>
                        <SeriesItems>
                            <telerik:CategorySeriesItem Y="10" />
                            <telerik:CategorySeriesItem Y="30" />
                            <telerik:CategorySeriesItem Y="20" />
                            <telerik:CategorySeriesItem Y="25" />
                        </SeriesItems>
                    </telerik:ColumnSeries>
                </Series>
            </PlotArea>
        </telerik:RadHtmlChart>

When there is no data in the source of the chart, the plot area should be displaying a message in predefined format. Something similar to what we have in the Grid and other controls.