How can I prevent more than one tag to be selected at once on a ExtJs Sencha tagfield?

Question

How can I prevent more than one tag to be selected at once on a ExtJs Sencha tagfield? I also want only one to be selected and once the element is selected to stay selected. When I set multiSelect: false if I insert new elements to the control I got an error message.

This a fiddle with the example. If you press shift key you'll be able to select more than one. I only want to have one selected.

    Ext.application({
    name : 'Fiddle',

    launch : function() {
        var shows = Ext.create('Ext.data.Store', {
            fields: ['id','show'],
            data: [
                {id: 1, show: 'Tag 1'},
                {id: 2, show: 'Tag 2'},
                {id: 3, show: 'Tag 3'}
            ]
        });

        Ext.create('Ext.window.Window', {
            //renderTo: Ext.getBody(),
            title: 'Tagfield Test',
            height: 200,
            width: 500,
            layout: 'fit',
            items: [{
                xtype: 'tagfield',
                fieldLabel: 'Pick a tag',
                store: shows,
                displayField: 'show',
                valueField: 'id',
                queryMode: 'local',
                filterPickList: true,
                minWidth: 300,
                maxWidth: 200,
                maxHeight: 10
            }]
        }).show();
    }
});

https://fiddle.sencha.com/#view/editor&fiddle/38o7

Two tags selected at the same time

Answer 1

Change selection model mode after rendering of the tagField:

Ext.application({
    name : 'Fiddle',

    launch : function() {
        var shows = Ext.create('Ext.data.Store', {
            fields: ['id','show'],
            data: [
                {id: 1, show: 'Tag 1'},
                {id: 2, show: 'Tag 2'},
                {id: 3, show: 'Tag 3'}
            ]
        });

        Ext.create('Ext.window.Window', {
            //renderTo: Ext.getBody(),
            title: 'Tagfield Test',
            height: 200,
            width: 500,
            layout: 'fit',
            items: [{
                xtype: 'tagfield',
                fieldLabel: 'Pick a tag',
                store: shows,
                displayField: 'show',
                valueField: 'id',
                queryMode: 'local',
                filterPickList: true,
                minWidth: 300,
                maxWidth: 200,
                maxHeight: 10,
                // Change selection model mode after render.
                listeners: {
                    afterrender: function(tagField) {
                        tagField.selectionModel.setSelectionMode('SINGLE');
                    }
                }
            }]
        }).show();
    }
});

Answer 2

Add a configuration on your tagfield...

multiSelect: false

https://docs.sencha.com/extjs/7.2.0/classic/Ext.form.field.Tag.html#cfg-multiSelect