Is this a bug or am i missing something?

I have a tabPanel and 2 Tabs within the Panel (tabEmpty and tabChart). Unless i have the tabPanel point (eg set selectedTab="tabChart" ) to the Tab with the Chart in it, tabChart, the chart won't show up (it actually shows up but crammed way up into the left corner with just a few pixels showing.)

What am i missing? If you change the selectedTab to tabChart, you'll see it correctly.
Here's the code:

**********the page***************
<apex:page controller="PieChartController" title="Pie Chart">
    <apex:tabPanel switchType="client" selectedTab="tabEmpty" id="AccountTabPanel">
 
    <!--    **************Empty Tab *********************************-->
    <apex:tab label="Empty Tab" name="tabEmpty" id="tabEmpty">
    </apex:tab>

    <!--    **************Tab with a Chart***************************-->
    <apex:tab label="Chart Tab" name="tabChart" id="tabChart">
        <apex:chart resizable="true" height="350" width="450" data="{!pieData}">
            <apex:pieSeries dataField="data" labelField="name"/>
            <apex:legend position="right"/>
        </apex:chart>
    </apex:tab>
    
    </apex:tabPanel>    
</apex:page>


**********and the PieChartController controller***************
public class PieChartController {
    public List<PieWedgeData> getPieData() {
        List<PieWedgeData> data = new List<PieWedgeData>();
        data.add(new PieWedgeData('Jan', 30));
        data.add(new PieWedgeData('Feb', 15));
        data.add(new PieWedgeData('Mar', 10));
        data.add(new PieWedgeData('Apr', 20));
        data.add(new PieWedgeData('May', 20));
        data.add(new PieWedgeData('Jun', 5));
        return data;
    }

    // Wrapper class
    public class PieWedgeData {

        public String name { get; set; }
        public Integer data { get; set; }

        public PieWedgeData(String name, Integer data) {
            this.name = name;
            this.data = data;
        }
    }
}