Hi Markus,

I'm running on Windows 7. I tried to remove all subscription providers and keep only NewsletterStudio one but the issue is still there, even if the list has only one item.

I tried to inspect the multiselect widget and I saw that after I de-select an option the related hidden select option maintains the "selected" attribute set to "selected".

So, I debugged the umbraco/newsletterstudio/js/ui.dropdownchecklist-1.3-min.js script file and I saw that the _syncSelected function inside it performs the sync between the widget ui and the hidden select input. Inside that function there is a for each loop that sets the "selected" attribute of the hidden select input options starting from the widget "checked" items. I changed that code in order to set the "selected" attribute when the widget item is checked and to remove the "selected" attribute when the widget item is un-checked. Now it works (I tested this solution with Chrome, Firefox and IE).

I don't know if I'm the only one having this issue, however I hope that my explanation is clear enough and this code can be helpful for anyone facing with the same issue ;)

Here is the code.

_syncSelected: function (g) {
    var h = this,
                j = this.options,
                b = this.sourceSelect,
                d = this.dropWrapper;
    var c = b.get(0).options;
    var f = d.find("input.active");
    if (j.firstItemChecksAll) {
        if ((g == null) && a(c[0]).attr("selected")) {
            f.attr("checked", true)
        } else {
            if ((g != null) && (g.attr("index") == 0)) {
                f.attr("checked", g.attr("checked"))
            } else {
                var e = true;
                var i = null;
                f.each(function (k) {
                    if (k > 0) {
                        var l = a(this).attr("checked");
                        if (!l) {
                            e = false
                        }
                    } else {
                        i = a(this)
                    }
                });
                if (i != null) {
                    i.attr("checked", e)
                }
            }
        }
    }
    f = d.find("input");
    f.each(function (k) {
        /* original code *****************/
        //a(c[k]).attr("selected", a(this).attr("checked"))
        /*********************************/

        /* new code *********************/
        var x = a(this);
        if (a(this).attr("checked")) {
            a(c[k]).attr("selected", a(this).attr("checked"));
        } else {
            a(c[k]).removeAttr("selected");
        }
        /**********************************/
    });
    h._updateControlText();
    if (g != null) {
        g.focus()
    }
}

Regards

Matteo