Apache – developing sites with Flex applications

Here's a code segment where I do what I think you're describing. The images are various sizes, but this displays them in a squared-up grid. The trick (at least for my requirements) is to set the height and minWidth for the container that goes into each cell.

<mx:TileList id="imgTiles" width="100%" height="100%"  
      paddingTop="2" paddingBottom="2" paddingLeft="2" paddingRight="2"  
      itemClick="eTilesClick(event)">     
    <mx:itemRenderer>  
        <mx:Component>  
            <mx:VBox horizontalAlign="center"  
                   height="250" minWidth="150"  
                   horizontalScrollPolicy="off" verticalScrollPolicy="off"  
                   borderColor="#D2D2D2" borderThickness="1"
                   borderStyle="solid">
                <mx:Label text="{data.imageCaption}" height="15" fontSize="10" fontWeight="bold"/>
                <mx:Image source="{data.thumbnailUrl}" width="100%"/>
            </mx:VBox>
        </mx:Component>
    </mx:itemRenderer>
</mx:TileList>

If both applications are running at the same time on the same machine, you could open up a LocalConnection between the two applications to send information between them. See the LocalConnection documentation for more info.