The following example shows how you can set the horizontal scroll policy on a Spark DropDownList control in Flex 4 by setting the horizontalScrollPolicy style on the drop down menu’s Scroller skin part.

The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see http://www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.
For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/02/06/setting-the-horizontal-scroll-policy-on-a-spark-dropdownlist-control-in-flex-4/ -->
<s:Application name="Spark_DropDownList_scroller_horizontalScrollPolicy_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx">
 
    <fx:Script>
        <![CDATA[
            import mx.core.ScrollPolicy;
        ]]>
    </fx:Script>
 
    <s:DropDownList id="ddl"
            width="100"
            horizontalCenter="0" top="20"
            open="ddl.scroller.setStyle('horizontalScrollPolicy', ScrollPolicy.OFF);">
        <s:dataProvider>
            <s:ArrayList source="[Accordion,ApplicationControlBar,Alert,Box,Button,ButtonBar,Canvas,ColorPicker]" />
        </s:dataProvider>
    </s:DropDownList>
 
</s:Application>

View source is enabled in the following example.

Or you can set the horizontalScrollPolicy style in an external .CSS file or <Style/> block, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/02/06/setting-the-horizontal-scroll-policy-on-a-spark-dropdownlist-control-in-flex-4/ -->
<s:Application name="Spark_DropDownList_scroller_horizontalScrollPolicy_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx">
 
    <fx:Style>
        @namespace s "library://ns.adobe.com/flex/spark";
 
        s|Group#dropDown #scroller {
            horizontalScrollPolicy: off;
        }
    </fx:Style>
 
    <s:DropDownList id="ddl"
            width="100"
            horizontalCenter="0" top="20">
        <s:dataProvider>
            <s:ArrayList source="[Accordion,ApplicationControlBar,Alert,Box,Button,ButtonBar,Canvas,ColorPicker]" />
        </s:dataProvider>
    </s:DropDownList>
 
</s:Application>

This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.

 
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About The Author

Peter deHaan

Peter deHaan currently works for Adobe on the Flex SDK QA team. While not working on Flex, Flash, and ColdFusion applications, Peter enjoys making up bios and writing in 3rd person. Peter's rarely updated blog can be found at blogs.adobe.com/pdehaan/, actionscriptexamples.com, airexamples.com, and coldfusionexamples.com.

2 Responses to Setting the horizontal scroll policy on a Spark DropDownList control in Flex 4

  1. Mani says:

    Oh my God! Thank you!

  2. Saariko says:

    how about auto resizing the dropdown width to fit all the content?
    is that possible?

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