Flex 3 rowCount thing for combobox happen in flex 4

Question

I can't find a way to have the flex 3 rowCount thing for combobox happen in flex 4. I tried this:
<s:ComboBox id="cb" width="240">
                <s:layout>
                    <s:VerticalLayout requestedRowCount="25" >
                    </s:VerticalLayout>
but no change

Answer 1

Heres a skin you could try for the cb lol
<?xml version="1.0" encoding="utf-8"?>
<!--
ADOBE SYSTEMS INCORPORATED
Copyright 2008 Adobe Systems Incorporated
All Rights Reserved.
NOTICE: Adobe permits you to use, modify, and distribute this file
in accordance with the terms of the license agreement accompanying it.
-->
<!--- The default skin class for the Spark DropDownList component.
The skin for the anchor button for a DropDownList component
is defined by the DropDownListButtonSkin class.
<p>In a custom skin class that uses transitions, set the
<code>itemDestructionPolicy</code> property to <code>none</code>
for the PopUpAnchor defined by the popUp property.</p>    
@see spark.components.DropDownList       
@see spark.skins.spark.DropDownListButtonSkin
@langversion 3.0
@playerversion Flash 10
@playerversion AIR 1.5
@productversion Flex 4
-->
<s:SparkSkin xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark"
             xmlns:fb="http://ns.adobe.com/flashbuilder/2009" alpha.disabled=".5">
    <!-- host component -->
    <fx:Metadata>
        <![CDATA[
        * @copy spark.skins.spark.ApplicationSkin#hostComponent
        [HostComponent("spark.components.DropDownList")]
        ]]>
    </fx:Metadata>
    <fx:Script fb:purpose="styling">
        <![CDATA[           
            /* Define the content fill items that should be colored by the "contentBackgroundColor" style. */
        //    static private const contentFill:Array = ["bgFill"];
             * @private
        //    override public function get contentItems():Array {return contentFill};
             * @private
            override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
                if (getStyle("borderVisible") == false)
                    if (border)
                        border.visible = false;
                    if (background)
                        background.left = background.top = background.right = background.bottom = 0;
                    if (scroller)
                        scroller.minViewportInset = 0;
                else
                    if (border)
                        border.visible = true;
                    if (background)
                        background.left = background.top = background.right = background.bottom = 1;
                    if (scroller)
                        scroller.minViewportInset = 1;
                if (dropShadow)
                    dropShadow.visible = getStyle("dropShadowVisible");
                openButton.setStyle("cornerRadius", getStyle("cornerRadius"));
                if (borderStroke)
                    borderStroke.color = getStyle("borderColor");
                    borderStroke.alpha = getStyle("borderAlpha");
                super.updateDisplayList(unscaledWidth, unscaledHeight);
        ]]>
    </fx:Script>
    <s:states>
        <s:State name="normal" />
        <s:State name="open" />
        <s:State name="disabled" />
    </s:states>
    <!---
    The PopUpAnchor control that opens the drop-down list.
    <p>In a custom skin class that uses transitions, set the
    <code>itemDestructionPolicy</code> property to <code>none</code>.</p>
    -->
    <s:PopUpAnchor id="popUp"  displayPopUp.normal="false" displayPopUp.open="true" includeIn="open"
                   left="0" right="0" top="0" bottom="0" itemDestructionPolicy="auto"
                   popUpPosition="below" popUpWidthMatchesAnchorWidth="true">
        <!---
        This includes borders, background colors, scrollers, and filters.
        @copy spark.components.supportClasses.DropDownListBase#dropDown
        -->
        <s:Group id="dropDown" maxHeight="800" minHeight="22" >
            <!--- @private -->
            <s:RectangularDropShadow id="dropShadow" blurX="20" blurY="20" alpha="0.45" distance="7"
                                     angle="90" color="#000000" left="0" top="0" right="0" bottom="0"/>
            <!--- @private -->
            <s:Rect id="border" left="0" right="0" top="0" bottom="0">
                <s:stroke>
                    <!--- border stroke @private -->
                    <s:SolidColorStroke id="borderStroke" weight="1"/>
                </s:stroke>
            </s:Rect>
            <!-- fill -->
            <!--- Defines the appearance of drop-down list's background fill. -->
            <s:Rect id="background" left="1" right="1" top="1" bottom="1" >
                <!--    <s:SolidColor id="bgFill" color="0xFFFFFF" />-->
                <s:stroke>
                    <s:SolidColorStroke color="#555555" />
                </s:stroke>
                <s:fill >
                    <s:LinearGradient rotation="75" >
                        <s:GradientEntry color="0x0e47a5"  />
                        <s:GradientEntry color="0x27c1f4" />
                        <s:GradientEntry color="0x0e47a5" />
                    </s:LinearGradient>
                </s:fill>  
            </s:Rect>
            <!--- @private -->
            <s:Scroller id="scroller" left="0" top="0" right="0" bottom="0" hasFocusableChildren="false" minViewportInset="1">
                <!--- @copy spark.components.SkinnableDataContainer#dataGroup-->
                <s:DataGroup id="dataGroup" itemRenderer="spark.skins.spark.DefaultItemRenderer">
                    <s:layout>
                        <s:VerticalLayout gap="0" horizontalAlign="contentJustify" requestedRowCount="15"/>
                    </s:layout>
                </s:DataGroup>
            </s:Scroller>
        </s:Group>
    </s:PopUpAnchor>
    <!---  The default skin is DropDownListButtonSkin.
    @copy spark.components.supportClasses.DropDownListBase#openButton
    @see spark.skins.spark.DropDownListButtonSkin -->
    <s:Button id="openButton" left="0" right="0" top="0" bottom="0" focusEnabled="false"
              skinClass="spark.skins.spark.DropDownListButtonSkin" /> 
    <!--- @copy spark.components.DropDownList#labelDisplay -->
    <s:Label id="labelDisplay" verticalAlign="middle" maxDisplayedLines="1"
             mouseEnabled="false" mouseChildren="false"
             left="7" right="30" top="2" bottom="2" width="75" verticalCenter="1" />
</s:SparkSkin>