<p>I'm playing with <a href="http://www.dncompute.com/blog/2007/03/19/seed-based-pseudorandom-number-generator-in-actionscript.html" rel="nofollow noreferrer">this ActionScript</a> which generates a random 'squiggle'.</p>

<p>Each time a 'squiggle' is placed, it appears within a sprite with a white background.</p>

<p>If I change the background colour of the flash file to pink for example, it would still show up as white.</p>

<p>Does anybody know how I might make the sprite background transparent? Thanks.</p>

That is not an actual Sprite (Sprite is an AS3 datatype) it's just a MovieClip that's called 'sprite'. I see that in the code the squiggles are actually being drawn to a MovieClip called 'paintSurface', then when it's done a Bitmap of 'paintSurface' is captured via this line:
```
```
bitmapData.draw(paintSurface);
```
```
then it is attached to the 'sprite' MovieClip here:
```
```
sprite.attachBitmap(bitmapData, 3);
```
```
That is probably why you are getting the white background.
I assume the bitmap is being captured for the sake of processing speed.
Perhaps you could see what happens if you do not capture a bitmap, but instead just attach 'paintSurface' to 'sprite' instead.