select an item from the dropdown, different than "1"
expected: buttons become enabled
actual: radbutton is still disabled
<asp:Button ID="ButtonTest" runat="server" enabled="true" Text="Test" EnableViewState="False" />
<telerik:RadPushButton ID="RadButtonTest" runat="server" Text="RadButtonTest" Enabled="True" EnableViewState="False" RenderMode="Lightweight"></telerik:RadPushButton>
<asp:DropDownList runat="server" ID="DropDownTest" AutoPostBack="True" OnSelectedIndexChanged="SelectedIndexChanged_Test">
    <Items>
        <asp:ListItem Text="1" Value="1"></asp:ListItem>
        <asp:ListItem Text="2" Value="2"></asp:ListItem>
        <asp:ListItem Text="3" Value="3"></asp:ListItem>
        <asp:ListItem Text="4" Value="4"></asp:ListItem>
    </Items>
</asp:DropDownList>
 
protected void Page_LoadComplete(object sender, EventArgs e)
{
    if (DropDownTest.SelectedValue == "1")
    {
        ButtonTest.Enabled = false;
        RadButtonTest.Enabled = false;
    }
    else//workaround
    {
        string script = string.Format("function f(){{$find('{0}').set_enabled({1});Sys.Application.remove_load(f);}}Sys.Application.add_load(f);",
                                            RadButtonTest.ClientID,
                                            "true");
        ScriptManager.RegisterStartupScript(Page, Page.GetType(), "someKey", script, true);
    }
}

protected void SelectedIndexChanged_Test(object sender, EventArgs e)
{
}

Implementing a fix for the Lightweight RenderMode is likely to cause regressions:
- https://feedback.telerik.com/Project/108/Feedback/Details/166590-fix-the-compatibility-of-radbutton-in-lightweight-with-image-in-cookieless-sessio
- https://feedback.telerik.com/Project/108/Feedback/Details/66505-fix-the-compatibility-of-radbutton-with-custom-image-that-contains-special-symbol

Thus, there are several workarounds:
- use the Classic RenderMode, if possible
- use the script below
- use CSS to set the icon instead of a property (example further down)

JS workaround:
			<telerik:RadButton runat="server" ID="rb1" RenderMode="Lightweight">
				<Icon PrimaryIconUrl="~/Circle_Green_20.png" />
			</telerik:RadButton>
			<telerik:RadPushButton runat="server" ID="rpb1" text="sample text">
				<Icon Url="Circle_Green_20.png" />
			</telerik:RadPushButton>
			<script>
				function repaintButtons() {
					$telerik.$(".RadButton.rbIconButton, .RadButton.rbIconOnly").each(function (index, elem) {
						if (elem && elem.control && elem.control.repaint) {
							elem.control.repaint();
						}
					});
					//uncomment this if you want the method to fire after each partial postback as well
					//Sys.Application.remove_load(repaintButtons);
				}
				Sys.Application.add_load(repaintButtons);
			</script>


CSS workaround:

			<telerik:RadButton runat="server" ID="rb1" RenderMode="Lightweight" CssClass="myCustomIcon" Text="some text">
				<Icon PrimaryIconUrl="Circle_Green_20.png" />
			</telerik:RadButton>
			<style>
				.myCustomIcon .rbPrimaryIcon
				{
					background-image: url(Circle_Green_20.png);
				}
			</style>

Declined with the following description:
Telerik controls can be found on the client-side through the findControl() method exposed by the Telerik client static library (http://www.telerik.com/help/aspnet-ajax/telerik-static-client-library.html). For example:
JavaScript:
	<telerik:RadCodeBlock ID="RadCodeBlock1" runat="server">
		<script>
			function pageLoad() {
				var btn1 = $get("<%=RadButton1.ClientID %>");
				var btn2 = $telerik.findControl(btn1, "RadButton2");
				btn2.set_text("New text");
			}
		</script>
	</telerik:RadCodeBlock>
ASPX:
		<telerik:RadButton runat="server" ID="RadButton1" Width="190"
			Height="190">
			<ContentTemplate>
				<span>RadButton Content</span>
				<telerik:RadButton ID="RadButton2" runat="server" Text="OldText" />
			</ContentTemplate>
		</telerik:RadButton>

Declined with the reason:

Item is a duplicate of http://feedback.telerik.com/Project/108/Feedback/Details/127356

Checkbox buttons are missing when ToggleType='CustomToggle' in Lightweight rendering. The issue is introduced in 2017 R1 release.

Code to reproduce:
        <telerik:RadButton runat="server" ID="btnEnableTrace" RenderMode="Lightweight"
            ButtonType="ToggleButton" ToggleType="CustomToggle">
            <ToggleStates>
                <telerik:RadButtonToggleState PrimaryIconCssClass="rbToggleCheckbox"></telerik:RadButtonToggleState>
                <telerik:RadButtonToggleState PrimaryIconCssClass="rbToggleCheckboxChecked"></telerik:RadButtonToggleState>
            </ToggleStates>
        </telerik:RadButton>

Just updated the controls and as usual got bitten by the change.  Very simple, we had a button that changed colors based on a change in an edit page.  The Button remained a White Color if nothing was entered, a Green Color if the fields were all correct and a Red Color if the fields were in error.  The determining factor is all behind the seen analysis on a save which has nothing to do with the Button.  Code behind the scenes sets a db value for the status of the Button. We know that the status is being set correctly because activity allowed or disallowed occurs correctly and that the DB settings having been checked are 100% correct as well.

There are seven Buttons with 7 Entry Pages that are affected and the users are totally confused when there is no visual direction as to the problem.

How do we Fix the Button to change Colors