How can we setup a prefix namespace for a custom library in FB 4.7

Question

Using 3.6, we are creating a custom library.
We need to be able to use a prefix such as "MyLib" when adding library components to an MXML file in an application.
Right now we get <ns:MyButton. . .> and we need <myLib:MyMyButton . . .>. Any other library used gets <ns1:...<ns2:... etc. Not very usefull to identify the source of the component.
In the library, we have the manifest.xml and design.xml. The library is functional except for the prefix.
manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<componentPackage>
          <component id="MyButton" class="com.test.MyButton"/>
</componentPackage>
design.xml
<?xml version="1.0"?>
<design version="2">
          <namespaces>
                    <namespace prefix="myLib" uri="library://flex/myLib"/>
          </namespaces>
          <categories>
                    <category id="MyLib" defaultExpand="true"/>
          </categories>
          <components>
                    <component name="MyButton" namespace="myLIb" category="MyLib" displayName="MyButton"/>
          </components>
</design>
When building the SWC, the assets includes the manifest.xml and design.xml files. The Namespace URL library://flex/myLib and manifest file location are also set. The compiler arguments contains -include-namespaces library://flex/myLib
Is there  fix for this?
I understand that the "design" part has been removed from 4.7, but why would it affect the mxml prefix?

Answer 1

Any feedback from Adobe people that worked on FB 4.7 and the removeal of the design mode?
Are they related? Any suggestions?
Having random namespace prefix being generated is very annoying.