I was browsing through the documentation like i had many times before, but this time i noticed the offscreenExtraRowsOrColumns property. At first you think “wtf” but then i got curious…

Say you have 25 images in a grid that displays one row of 5 images at a time:

The row in green will be the only row visible at this point in time. When you scroll, Flex will chuck out the first row and create the second row:

…and so on. Isn’t that just damn irritating? (If you’re thinking “nah, what’s the big deal?” then you obviously haven’t tried this before).

Anyway, the way to fix it is to tell Flex how many rows there are offscreen so that it can create them in the interim. This seems like a bit of a weird method because in the navigator classes (ViewStack, et al) there is a creationPolicy property which – when set to “all” – will create all the non-visible components before they’re navigated to, thus slowing down the processing a bit (depending on your app) but also speeding up the switch between views. Alas, no such property to be found in the TileList component. Can anybody tell me why? I think i should code a modified version of the TileList component to accept this property… +1 to TODO list… *sigh*

Hopefully this will help those of you experiencing the ball-ache that i did.