Un semplice Style per cambiare lo stile delle scrollbar in Flex, ovviamente deve essere aggiunto al tag .

.dropDownStyle
{
    vertical-scroll-bar-style-name : "scrollStyle";
    font-family:Arial;
    font-size:10;
    font-weight:normal;
    kerning:true;
    color:#000000;
    background-color:#E5E5E5;

}

.scrollStyle
{

    downArrowDownSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollArrowDown_downSkin");
    downArrowOverSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollArrowDown_overSkin");
    downArrowUpSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollArrowDown_upSkin");

    thumbDownSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollThumb_upSkin");
    thumbOverSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollThumb_upSkin");
    thumbUpSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollThumb_upSkin");

    trackSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollTrack_Skin");

    upArrowDownSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollArrowUp_downSkin");
    upArrowOverSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollArrowUp_overSkin");
    upArrowUpSkin: Embed(source="../flashobjects/ScrollBar.swf",
symbol="scrollArrowUp_upSkin");

} 

Tra gli apici ( “…” ) deve essere messo il path dove trovare l’swf con il nuovo stile della ScrollBar.