Flex Advanced data grid:column visibility

HI I am new to Flex and was wondering, when we use an advanced data grid, only when we click on the parent element the children details get populated in the corr开发者_开发知识库esponding columns, right?..SO now i have made the empty columns invisible(at design) now how do i make them visible at run time when the parent element is expanded..similarly once the columns are visible, how can i make them invisible again when the parent element is closed. Please help me out

Thanks

I think the event you want to listen for is "itemOpen" then the function you want will be something like:

MyADG.columns[invisible column index].visible=true;