So here is the situation, you want to display data in a ComboBox and make sure the user chooses something from the dropdown. You do not want the first thing showing to be real data as this could cause the user to leave it as is and also void your validation routine. So, you decide that you will all a blank as the first position by adding an empty value to the Array that is the dataProvider for the ComboBox like this:
private var dataP1:Array = [”, ‘one’,'two’,'three’,'four’,'five’,’six’,’seven’,'eight’,'nine’,'ten’];
Doing this exposes a bug within the ComboBox where the value will be replaced by a blank space on each repeat of the rowCount property. The example below has the rowCount set to 3 which is why you see one, two and then a blank where three should be. If you were to change the rowCount to , the blank would then show where the five and ten should have been.
A workaround is to use an blank space instead of an empty string in the first position of the Array like this:
private var dataP2:Array = [’ ‘,’one’,'two’,'three’,'four’,'five’,’six’,’seven’,'eight’,'nine’,'ten’];
However, all of this mess can be avoided by simply using the prompt property to add the blank space at the top of the ComboBox. It should also be noted that the blank space added by the prompty property actually sits at a selectedIndex of -1 while the workarouns above would have the blank space at a selectedIndex of 0. This doesn’t effect then functionality of the ComboBoxbut should be taken into consideration when validating.
