ListGrid stuck in "Data Loading" when fetchData is called before the first finishes

[lchen]

SmartClient Version: v9.0p_2013-11-03/PowerEdition
Browsers: IE 8-10, Chrome 32, probably others

I have a ListGrid that fetches data from a DataSource based on user interaction with other components. Sometimes the user initiates another fetchData before the previous call to fetchData has completed. Whenever this happens the grid gets stuck in a "Loading Data" state.

There are no errors that occur on the server side and I can see the data coming back to the client just fine. The fetchData callback method for both fetchData requests also gets called without a problem. But the ListGrid never displays the rows. It just continues showing the "Loading Data" message.

You can duplicate this behavior by modifying the code in the example:
http://www.smartclient.com/#databoundFetch

isc.ListGrid.create({
    ID: "countryList",
    width:500, height:224, alternateRecordStyles:true,
    dataSource: worldDS,
    // display a subset of fields from the datasource
    fields:[
        {name:"countryCode"},
        {name:"countryName"},
        {name:"capital"},
        {name:"continent"}
    ],
    sortFieldNum: 1, // sort by countryName
    dataPageSize: 50,
    drawAheadRatio: 4
})

isc.IButton.create({
    left:1, top:240, width:160,
    title:"Fetch Double",
    click: function() {
       countryList.fetchData(
          {continent:'Europe'}, 
          function(dsResponse, data, dsRequest){
                isc.say('callback 1 '+dsRequest.clientContext.getDataSource().ID);
           }, 
          {clientContext: countryList}
       );
       setTimeout(function() {
         countryList.fetchData(
            {continent:'Africa'}, 
            function(dsResponse, data, dsRequest){
                isc.say('callback 2 '+dsRequest.clientContext.getDataSource().ID);
            }, 
            {clientContext: countryList}
         );
       }, 100);
    }
})

Any suggestions on why this might be happening and the best way to prevent the grid from getting stuck in the "Data Loading" state?

[Isomorphic]

Thanks for the clear test case. This is now fixed for 8.3, 9.0 and 9.1.