# AS3 - mask = null problem

**URL:** https://forum.kirupa.com/t/as3-mask-null-problem/308980
**Category:** flash
**Created:** [May 4, 2010, 3:40pm UTC](https://forum.kirupa.com/t/as3-mask-null-problem/308980 "2010-05-04T15:40:43Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![asscripter](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@asscripter](https://forum.kirupa.com/u/asscripter)
#### Post date: [May 4, 2010, 3:40pm UTC](https://forum.kirupa.com/t/as3-mask-null-problem/308980/1 "2010-05-04T15:40:43Z")

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Hi, I have a movieclip which is being masked using another movieclip. In one condition I want to unmask the mc. But seems mask = null isn’t working. Any idea how can I remove mask dynamically.

a.mask = b;  
a.width ++;

if(a.width \> 10)  
{  
a.mask = null; //nothing happens ☹  
}