Compare Date Parameters on Report Viewer

Question

Visual Studio 2010 (VB.NET)
Crystal Reports 2010
I have two date parameters in my report viewer (Start and End dates). When the user clicks the "Apply" button in the parameter panel is there any way to display a dialog box if the Start date is after the End date?
I don't see any event for the "Apply" button, just the "Refresh" button (the ReportRefresh event).

Answer 1

I actually got a hack job workaround to get this to work without having to write my own parameter panel or edit any of my 150+ reports:
At the form load I can loop through the controls in the crystal viewer until I find the toolbar that holds the "Apply" button and add an event handler to it's ButtonClick event.
I am using VB.NET:
'Because there is no event handler for the "Apply" button in the parameter panel,
'loop through the controls until we find the toolbar that holds that button. We can then
'add an event handler to the button click event so we can check if the "Apply" button is clicked.
For Each ctl As Control In CurrentCrystalReportViewer.Controls
    If ctl.Name = "InteractiveParameterPanel" Then
        'This control is the parameter panel
        For Each subCtl As Control In ctl.Controls
            If TypeOf subCtl Is Windows.Forms.ToolBar Then
                'This controls is the toolbar that holds the "Apply" and "Delete" parameter buttons
                Dim parmTool As ToolBar = subCtl
                'add event handle so we can catch when a button is clicked
                AddHandler parmTool.ButtonClick, AddressOf ParmToolBar_ButtonClick
                Exit For
            End If
        Next
    End If
Next
When the "Apply" button is clicked this event will then be called:
Private Sub ParmToolBar_ButtonClick(ByVal sender As Object, ByVal e As ToolBarButtonClickEventArgs)
        If e.Button.Text = "Apply" Then
            'check if there are date parameters
            If CurrentCrystalReportViewer.ParameterFieldInfo.Count > 0 Then
                  'loop through and find the start and end date parameters to compare the dates.
            End If
        End If
End Sub