It appears there is no prompt property for the spark Combobox component as there was with the mx version. Anyone have a simple work around for this or know something? Thanks in advance.
There are now two 'combobox' like components in Spark, fx:Combobox and fx:DropDownList. DropDownList has a prompt component and behaves quite a bit like the old flex 3 combobox. I think you'll just need to switch components and you should be able to set a prompt.
To solve this problem, just add this property to the s.ComboBox:
with this solution you can have a prompt without adding any row to your dataProvider
<s:ComboBox prompt="Test" /> works for me in Flex 4.6. If I remember correctly prompt support was added in Flex 4.5.