Ext JS : paginating search results needs to persist values of filter fields

var s = this.getStore();
s.baseParams.[[+name]] = tf.getValue();
this.getBottomToolbar().changePage(1);
this.refresh();

<script>
// Persist the filter value between page changes
function filterWriter(tf,nv,ov) {
    var grid = Ext.getCmp('articlesGrid');
    var store = grid.getStore();
    store.baseParams.createdby = tf.getValue();
}

Ext.onReady(function(){
    // create the Data Store
    var store = new Ext.data.JsonStore({
        // ... stuff here bla bla etc... 
        proxy: new Ext.data.HttpProxy({
            url: '{$url}' // <--- my special PHP p
        })
    });

    var grid = new Ext.grid.GridPanel({
        store: store,

        //... other stuff here

        // paging bar on the bottom
        bbar: new Ext.PagingToolbar({
            // xtype: 'paging', // assumed
            pageSize: 25,
            store: store,
            displayInfo: true,
            displayMsg: 'Displaying Records {0} - {1} of {2}',
            emptyMsg: 'No Records to display'
        })
    });
    // render it
    grid.render('articles-grid');

    // trigger the data store load with starting values
    store.load({params:{start:0, limit:25}});

// Then a bit later...

Ext.onReady(function(){
    Ext.QuickTips.init();

    // My various filter controls:
    var fpItems = [
        {
            xtype : 'combo',
            fieldLabel : 'Writer',
            forceSelection : true,
            displayField : 'name',
            valueField : 'id',
            hiddenName : 'createdby',
            allowBlank : true,
            typeAhead : true,
            loadingText : 'Loading...',
            minChars : 1,
            triggerAction : 'all',
            store : UserStore,
            listeners: {
                'change': {fn:this.filterWriter,scope:this}  // <-- persist the value!
            }
        }];

    var formPanel = new Ext.form.FormPanel({
        id : 'articlesFormPanel',
        renderTo : 'articles-searchform', 
        // ... etc...
        items : fpItems
    }); 
});
</script>
<h2>Article Finder</h2>
<div id="articles-searchform"></div>
<div id="articles-grid"></div>';