Inventory System in RPG - Dynamic Positioning

Hey fellas. I’ve got an inventory symbol (that is like an inventory page) similar to the MMO’s out there such as World of Warcraft, Fly ff etc. Inside the inventory asset (the asset was created in Flash CS4), I have a FlexContentHolder(since the game has recently been migrated to a full flex project). Inside the FlexContentHolder, I have a VBox & HBox flex components. I’m trying to dynamically position items such as weapons, headgear or w.e (all square shaped symbols), I don’t want to specify the x and y coordinate of every single thing. I looked up setting styles for a HBox, by doing myHbox.setStyle(“horizontalGap”, 50);, it sets the children of that HBox horizontal seperate by 50 pixels…but that doesn’t seem to work for some reason. All of this is being done at runtime. Can anyone point me in the right direction for dynamic position? The inventory is 3 rows by 14 columns btw. Any help is appreciated. Thanks.