Is it possible to put a background image to a component 'Group' with CSS? How?

In a component 'Group' I drag multiple pictures at one time I need to clean this component, but contains a component BitmapImage and I will not be erased:

        <s:Group id="droppedImages"  width="100%开发者_高级运维" height="100%">
        <s:BitmapImage id="bg" source="@Embed('lineal2.jpg')" width="1024" height="577" verticalCenter="0"/>
        </s:Group>

I do this:

while (droppedImages.numChildren > 0) droppedImages.removeElementAt(0);

Im try something like:

while (droppedImages.numChildren > 1 ) { 
    if(droppedImages.getChildAt(0).name != 'bg'){
        droppedImages.removeChildAt(0)
    }
}

Thanks for the help

The main problem I see is that you're confusing "children" and "elements". They are not compatible numbers.