Can't get static property to work in emberjs class using property bindings

I am trying to create a static property in an ember object (all instances should share the same property and react when it changes). In my case I have 4 different instances, if any of these instances changes the refresh property I want all 4 instances to react to it.

I have found that the refresh binding only executes for the current instance whereby I want it to execute for all instance given it is a static property.

        enabled : function() {
           ...
        }.property('refresh'),


        selectionChanged : function() { 
            ...
            this.incrementProperty('refresh');
        }.observes('selection')

I have tried creating the the refresh property using a mixin

    var AbstractControlMixin = Ember.Mixin.create({
        refresh : 0
    });

    var AbstractControl = Ember.Object.extend(AbstractControlMixin,{
       ...
    });

an using the reopen technique

var AbstractControl = Ember.Object.extend({
    ...
});

AbstractControl.reopen({
            refresh : 0
});

but neither is working.