<com:TContent ID="Content">
 	<h1>Issue 504 Test</h1>

    <com:TPanel ID="dlg" DefaultButton="subPanel.buttonOk" >
    <com:TTextBox ID="textbox1" />
    <com:TButton ID="buttonDummy" OnCommand="buttonDummyClick" Text="Dummy button" />
    Panel Content
    <com:TLabel ID="label1" />
    <com:TPanel ID="subPanel" >
        <com:TButton ID="buttonOk" OnCommand="buttonOkClick" Text="Ok button" />
    </com:TPanel>
    </com:TPanel>
 </com:TContent>