Mixins: props are not correctly mixed in when registered globally

[DotCoyote]

Duplicates #3957

Vue.js version

2.1.8

Reproduction Link

https://jsfiddle.net/CinKon/qwaacqon/1/

Steps to reproduce

Open DevTools. Console-Error:
[Vue warn]: Property or method "myText" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option. (found in root instance)

What is Expected?

Props that are imported via mixin should render without problems.

What is actually happening?

Console throws error, prop is not transmitted.

[posva]

the template should be outside of the app. Also the prop needs to be lower case due to html limitations: https://jsfiddle.net/posva/p6puekc3/

[DotCoyote]

OK, got it. Problem was that I didn't export the mixin var (export default buttonMixin)