Spinners on input field (editable mode) don't update immediateValue until input loses focus

[davidptm56]

Description

There's an editable paper-slider in an element of my app that's binded to some computed properties in my main page that update on the fly some information on screen. I want this to happen "instantly" on any input on the slider, but I'm having trouble with the input field "spinners",

I'm running (Polymer v1.7):

<paper-slider ... on-imediate-value-changed="immediate" editable></paper-slider>

<script>
    Polymer({
        is: 'element-name',
        properties: {
            ...
            value:    {
                type: Number,
                notify: true
            },
            ...
        },
    ...
    immediate: function(e) { this.value = e.target.immediateValue },
    ...
    });
</script>

Expected outcome

I expect that whenever user drags the slider or inputs a value, this.value updates instantly.

Actual outcome

It works flawless when dragging the knob or entering text on the edit input field. But when clicking on the "arrow buttons" that browsers show on numeric input fields (a.k.a. spinners), immediateValue only updates after first click, following clicks don't act the same way until mouse pointer moves.