Setting the width of the dropdown menu on a ComboBox control in Flex

The following example shows how you can set the width of the dropdown menu on a Flex ComboBox control by setting the dropdownWidth property.

Full code after the jump.

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/07/02/setting-the-width-of-the-dropdown-menu-on-a-combobox-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="top"
        backgroundColor="white">
 
    <mx:Array id="arr">
        <mx:Object label="One" />
        <mx:Object label="Two" />
        <mx:Object label="Three" />
        <mx:Object label="Four" />
        <mx:Object label="Five" />
        <mx:Object label="Six" />
        <mx:Object label="Seven" />
        <mx:Object label="Eight" />
        <mx:Object label="Nine" />
        <mx:Object label="Ten" />
    </mx:Array>
 
    <mx:ComboBox id="comboBox"
            dataProvider="{arr}"
            dropdownWidth="200" />
 
</mx:Application>

View source is enabled in the following example.

Due to popular demand, here is the “same” example in a more ActionScript friendly format:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/07/02/setting-the-width-of-the-dropdown-menu-on-a-combobox-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="top"
        backgroundColor="white"
        initialize="init();">
 
    <mx:Script>
        <![CDATA[
            import mx.controls.ComboBox;
 
            private var arr:Array;
            private var comboBox:ComboBox;
 
            private function init():void {
                arr = [];
                arr.push({label:"One"});
                arr.push({label:"Two"});
                arr.push({label:"Three"});
                arr.push({label:"Four"});
                arr.push({label:"Five"});
                arr.push({label:"Six"});
                arr.push({label:"Seven"});
                arr.push({label:"Eight"});
                arr.push({label:"Nine"});
                arr.push({label:"Ten"});
 
                comboBox = new ComboBox();
                comboBox.dataProvider = arr;
                comboBox.dropdownWidth = 200;
                addChild(comboBox);
            }
        ]]>
    </mx:Script>
 
</mx:Application>

6 thoughts on “Setting the width of the dropdown menu on a ComboBox control in Flex

  1. I want my combobx should increase or decrease the width depends on the item selected. if the selected item is bigge the length of the combobox should increase.

  2. I have a combobox with a width of 100% in an HDividedBox. When the user increases the size of the box the size of the combobox also increases, however the dropdownwidht remains the same (too small). What event can I listen for to know when to reset the size of the dropdownwidth? I tried listening for the RESIZE event and it never fired. I also tried listening for ”widthChanged” and it didn’t fire either. Any ideas?

  3. Hi Peter, i would like Adjust my combobox dropdownwidth property, but according of the length dataprovider label, exist calculatePreferredSizeFromData() but i can’t call the method… any idea for my question?

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