I’ve found these days some designers and even programmers not aware of the 9-slice scaling that Flash provides, and that’s why I’d like to introduce it here for those who does not know it either.
This feature allows you to determine the way a MovieClip is scaled. Doing that you will be able to resize without unwanted results like your MovieClip is distorted.
With tablets and smart phones on the market, it’s a good idea to resize our content accordingly to the area we have available, and here is where 9-slice scaling will help you out.
Look at the picture below and notice the rounded corners it has:
Now look at the difference we get after applying an horizontal resize of the MovieClip:
As you can see with 9-slice scaling we can achieve the result we really expect.
In order to enable this feature, you just need to open the Properties panel of the MovieClip and select Enable guides for 9-slice scaling as shown in the picture below:
Then when you edit the MovieClip it will show you the guides that you can easily adjust to your needs as seen in the following picture:
This scaling mode cannot be applied to Buttons or Graphics Symbols. The same applies when we nest them inside a MovieClip. The 9-scale scaling will only be applied to the compatible content.
It would be perfect to have 9-slice scaling for Bitmaps as a built-in capability in Flash, but meanwhile Grant Skinner created a nice solution called BitmapSlice9. It allows you to break your Bitmaps in pieces and use the 9-slice scaling with a great results!
UPDATE: You can download this example in Flash CS5 here.