Coolite 

  function markRow(record) {
        if (record.data.ChangedToday) {
            return 'changed-row';
        }
    }

<ext:Store runat="server" ID="BookingListStore" AutoLoad="true" GroupField="Date">
    <Reader>
        <ext:XmlReader Record="BookingOverviewEntry" IDPath="DateId">
            <Fields>
                <ext:RecordField Name="DateId" Type="Int" />
                <ext:RecordField Name="TicketNumber" Type="String" />
                <ext:RecordField Name="Date" Type="Date" />
                <ext:RecordField Name="StartTime" Type="String" />
                <ext:RecordField Name="EndTime" Type="String" />
                <ext:RecordField Name="Status" Type="String" />
                <ext:RecordField Name="RoomAnnotation" Type="String" />
                <ext:RecordField Name="Topic" Type="String" />
                <ext:RecordField Name="Participants" Type="Int" />
                <ext:RecordField Name="Annotation" Type="String" />
                <ext:RecordField Name="BeverageUrl" Type="String" />
                <ext:RecordField Name="CateringUrl" Type="String" />
                <ext:RecordField Name="ChangedToday" Type="Boolean"/>
                <ext:RecordField Name="CateringStatus" Type="int" />
                <ext:RecordField Name="BeverageStatus" Type="int" />
            </Fields>
        </ext:XmlReader>
    </Reader>
</ext:Store>


// grid...

  <View>
                        <ext:GroupingView ID="GroupingView1" runat="server" ForceFit="true" ShowGroupName="true"
                            EnableNoGroups="true" HideGroupedColumn="true">
                            <GetRowClass Fn="markRow" />
                        </ext:GroupingView>
                    </View>

 function markRow(record) {
        if (record.data.ChangedToday=='true') {  // instead of    if (record.data.ChangedToday) { which worked in 0.82
            return 'changed-row';
        }
    }

<ArrayOfBookingOverviewEntry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://services.etask.de/">
  <BookingOverviewEntry>
    <Id>1526</Id>
    <TicketNumber>018.000.005.444</TicketNumber>
    <Date>2010-03-09T00:00:00</Date>
    <StartTime>00:00</StartTime>
    <EndTime>00:00</EndTime>
    <RoomAnnotation>Büroraum check</RoomAnnotation>
    <Topic>2. Test</Topic>
    <Participants>1</Participants>
    <Annotation />
    <DateId>1526</DateId>
    <Status>gebucht</Status>
    <BeverageUrl>0</BeverageUrl>
    <CateringUrl>0</CateringUrl>
    <ChangedToday>true</ChangedToday>
    <CateringStatus>0</CateringStatus>
    <BeverageStatus>0</BeverageStatus>
  </BookingOverviewEntry>
  <BookingOverviewEntry>
    <Id>1536</Id>
    <TicketNumber>018.000.005.475</TicketNumber>
    <Date>2010-03-09T00:00:00</Date>
    <StartTime>14:00</StartTime>
    <EndTime>14:30</EndTime>
    <RoomAnnotation>Entwicklerbüro</RoomAnnotation>
    <Topic />
    <Participants>1</Participants>
    <Annotation />
    <DateId>1536</DateId>
    <Status>gebucht</Status>
    <BeverageUrl>1536</BeverageUrl>
    <CateringUrl>0</CateringUrl>
    <ChangedToday>false</ChangedToday>
    <CateringStatus>0</CateringStatus>
    <BeverageStatus>1</BeverageStatus>
  </BookingOverviewEntry>

if (record.data.ChangedToday) {