Custom DropBox - bring dropdown to front? (AS Solution pls)

hi!
i´m pretty new to flash so sry for maybe stupid questions.
i tried to write my own drop box as the one in flash doesn´t fit my design.
(I search for an AS solution to do this all per code no library clickiclicki pls)

roughly said my problem is: when i click on an older dropbox the dropdown menu goes out and is covered by “younger” components.

i did something like this:
DropBox(with CustomButton (showing selected item) and dropdownMC as childs)
-CustomButton
-DropDown(MC having CustomButtons as Childs)
–CustomButtonWithItem1
–CustomButtonWithItem2

question: how do i best solve this? it wont help to set the index of it high because the problem are other components to which this index has no relevance.
should i do something like get the stage an place and delete the dropdown there?
is there something i overlooked like a bring to front function?

thx a lot Asa