For the time being the following CSS workaround can be used:
CSS:
    <style type="text/css">
        .RadButton.rbSkinnedButton input {
            padding-left: 6px;
            padding-right: 10px;
            margin: 0;
        }
    </style>
ASPX:
        <telerik:RadComboBox ID="RadComboBoxDateTimeFilter" runat="server">
            <ItemTemplate>
                <telerik:RadButton ID="RadButtonApply" Text="Apply" AutoPostBack="false" runat="server" />
                <telerik:RadButton ID="RadButtonClear" Text="Clear" AutoPostBack="false" runat="server" />
            </ItemTemplate>
            <Items>
                <telerik:RadComboBoxItem Text="" Value="" Selected="true" />
                <telerik:RadComboBoxItem Text="" Value="" />
            </Items>
        </telerik:RadComboBox>

When EnableAutomaticLoadOnDemand="true" is set and no Height is specified, the first time RadComboBox is expanded only the topmost 3 or 4 items are visible.
The rest of the items become visible when they are hovered or if the ComboBox is expanded again.

Having a RadCombobox on a form and assign a EmptyMessage later containing a diacritical character, the EmptyMessage is treated like it has been entered as a value.
So it will make a call to the webservice using that value which it should not do.

Code example:
        protected void TestLinkButton_Click(object sender, EventArgs e)
        {
            this.CountryComboBoxControl.EmptyMessage = "Bitte wählen Sie ein Land*";
        }

When combo popups to the top of the page it goes out of the browser viewport.
Reproduce: 
A RadComboBox on the bottom of your page and the page height is larger than the viewport.
When you scroll down the page to the RadComboBox and open it the itembox (100+ items) height will be higher than the view port.
See attachment 'RadComboBox.png'

Also the auto shrink doesn’t work in this situation see attachment RadComboBox2.png

Selecting an item from the RadComboBox and then pressing Enter key, does not trigger the default button(if set) of the form/panel in IE and Chrome. The workaround is to handle the client-side OnClientKeyPressing event of the RadComboBox and manually trigger the clicking of the default button.For example:

ASPX:

    <asp:Panel ID="Panel1" runat="server" DefaultButton="RadButton1">
        <telerik:RadTextBox ID="RadTextBox1" runat="server">
        </telerik:RadTextBox>
        <asp:Label ID="Label1" Text="" runat="server" />
        <telerik:RadButton ID="RadButton1" runat="server" OnClick="OnClick1" Text="Click" />
        <telerik:RadComboBox ID="RadComboBox1" runat="server" OnClientKeyPressing="OnClientKeyPressing">
            <Items>
                <telerik:RadComboBoxItem Text="text1" Value="val1" />
                <telerik:RadComboBoxItem Text="text2" Value="val2" />
                <telerik:RadComboBoxItem Text="text3" Value="val3" />
            </Items>
        </telerik:RadComboBox>
    </asp:Panel>

JavaScript:
    <telerik:RadCodeBlock ID="RadCodeBlock1" runat="server">
        <script type="text/javascript">
            function OnClientKeyPressing(sender, args) {

                if (args.get_domEvent().keyCode == 13) {
                    $find("<%=RadButton1.ClientID %>").click();
                }
            }
        </script>
    </telerik:RadCodeBlock>

Using the .get_value() in the OnClientDropDownClosed event of RadComboBox, produces empty value. The OnClientSelectedIndexChanged event works fine, but I need to be able to kick off the javascript even if the selected index doesn't change. 

My RadComboBox element:

<telerik:RadComboBox ID="CustomerSearch" runat="server" Width="180" Height="160"  
        MarkFirstMatch="true"  AllowCustomText="true" CssClass="CustomerSearch" AutoPostBack="false" 
        EnableLoadOnDemand="true" EnableVirtualScrolling="true" OnItemsRequested="CustomerSearch_ItemsRequested" 
        OnClientDropDownClosed="searchnav" EmptyMessage="Select a customer" DataSourceID="dsCustomer" DataTextField="CustomerName" 
        DataValueField="NavPath" BackColor="White" Skin="Forest" />

My SQLDataSource element:
<asp:SqlDataSource ID="dsCustomer" runat="server"
    SelectCommand="CustomerSearchName" SelectCommandType="StoredProcedure">
</asp:SqlDataSource>

My Javascript:
<telerik:RadScriptBlock ID="RadScriptBlock1" runat="server">
    <script type="text/javascript">
        function searchnav(sender, args) {
            var iframe = document.getElementById('ctl00_iMainPages');
            iframe.src = sender.get_value();
        }
    </script>
</telerik:RadScriptBlock>

In the meantime you can use the following css workaround that will fix the issue: 

.rcbAutoWidthResizer .rcbScroll {
	overflow: visible !important;
}
 
/*To target IE 6, 7 and 8*/
@media \0screen\,screen\9 {
	.rcbAutoWidthResizer .rcbScroll {
		overflow: auto !important;
	}
}
 
/*To target IE 9 and 10*/
@media screen and (min-width:0\0) {
	.rcbAutoWidthResizer .rcbScroll {
		overflow: auto !important;
	}
}

If we dynamically remove highlighted item from a ComboBox at clientside, afterwards get_highlightedItem still returns that deleted item.
ComboBox takes care of deleting selected item at like 497 of RadComboBox.js. Highlighted item should be taken care of too.

Hi There,
i am working on asp.net 4.0 with telerik asp.net ajax control. The problem i am facing is that all the controls are not working but the same files were working in asp.net 3.5, for example i am attaching a error page which is showing a radcombobox as a text box. I am not being able to figure out the issue/bug whether it is because of RadStyleSheetManager or RadScriptManager.

Kindly help me with this issue.

rad combobox on clientblur event setting custom text fine when we are going to press tab  key but we are getting issue when we are selecting item from rad combo box manually using mouse.on clicking suppose i have text :  ils - apple  i have called onclien

There is no RTL boundary detection in ComboBox, e.g. no _elementOverflowsLeftScreenBorder in RadComboBox.DropDown.js

RadComboBox will open up in case that ScreenBoundaryDetection is enabled and there is not enough space below even if the space above is much less than below.
Like in a vertically narrow frame with the ComboBox being at the top of the page. 
It seems better to compare the space below with above and put it where there is more space.

We are using the combo box drop down:

                <telerik:RadComboBox ID="rcbAccounts" runat="server" Width="360" DropDownWidth="810" OffsetX="-200"
                    DataValueField="AcctNumber" DataTextField="DisplayString" AutoPostBack="True"
                    AllowCustomText="True" Filter="Contains" ExpandDelay="0" CollapseDelay="0" MaxHeight="300"
                    OnClientDropDownOpening="OnRcbAccountsOpening" Skin="CustomTelerikSkin" EnableEmbeddedSkins="false"
                    EnableViewState="false" EnableScreenBoundaryDetection="true" >
                    <HeaderTemplate>
                        <ul>
                            <li class="rcbColumn" style="width: 330px">Name</li>
                            <li class="rcbColumn" style="width: 70px">Acct #</li>
                            <li class="rcbColumn" style="width: 90px">Type</li>
                            <li class="rcbColumn" style="width: 150px">Address</li>
                            <li class="rcbColumn" style="width: 110px">City</li>
                        </ul>
                    </HeaderTemplate>
                    <ItemTemplate>
                        <ul>
                            <li class="rcbColumn" style="width: 330px">
                                <%#DataBinder.Eval(Container.DataItem, EC.ACCT_NAME).ToString()%></li>
                            <li class="rcbColumn" style="width: 70px">
                                <%#DataBinder.Eval(Container.DataItem, EC.ACCT_NO).ToString()%></li>
                            <li class="rcbColumn" style="width: 90px">
                                <%#DataBinder.Eval(Container.DataItem, EC.ACCT_TYPE).ToString()%></li>
                            <li class="rcbColumn" style="width: 150px">
                                <%#DataBinder.Eval(Container.DataItem, EC.ACCT_ADDR1).ToString()%></li>
                            <li class="rcbColumn" style="width: 110px">
                                <%#DataBinder.Eval(Container.DataItem, EC.ACCT_CITY).ToString()%></li>
                        </ul>
                    </ItemTemplate>
                </telerik:RadComboBox>

It looks like the attached at runtime.  My question is:  Can we align the dropdown area to be left-aligned with the control?  In some cases, the left part of the data gets cut off by the browser window.

Hello,

I have a resize problem for Radcombobox .I can't change the height of default textbox of combobox.

Could you please help me?

When RadCombobox is inside fixed div element and is expanded it doesn't scroll as expected. The dropdown container should stay fixed as the combo's input element.