import stores from 'vue-stores'
Vue.use(stores)

new Vue({
  ...  
  data: {
    state: {
      showModal: false,
      global: {
        txt: 'shared Text'
      }
    }
  },
  methods: {
    toast(){
      alert(this.state.global.txt)
    }
  }
  ...
})

export default {
  ...
  methods: {
    toggle(){
      this.modal = !this.modal
    }
  },
  stores: {
    txt: 'state.global.txt',
    modal: 'state.showModal',
    alert(){
      return 'toast'
    }
  }
  ...
}