Passing variables between GUI and function to be executed

To all

I am trying to pass inputs from a UI styler (the GUI) to a function to be executed. The GUI is used to select a xls file and specified a tab in this xls. This works fine.

In the apply_cb() function I have

xlFileNameToOpen = nativeFileBrowser0.GetProperties.GetString("Path")
If xlFileNameToOpen = "" Then
theNXMessageBox.Show(theNXMessageBoxTitle, NXMessageBox.DialogType.Error, "Excel file to use is not specified")
errorCode = 1
Else
theLW.WriteLine ("Excel file to process: "& xlFileNameToOpen)
End If

xlSheetNameToUse = strTabSelect.GetProperties.GetString("Value")
If xlSheetNameToUse = "" Then
theNXMessageBox.Show(theNXMessageBoxTitle, NXMessageBox.DialogType.Error, "Tab to use is not specified")
errorCode = 1
Else
theLW.WriteLine ("Tab to use in supplied file: "& xlSheetNameToUse)
End if

' Proceed if everything is OK
If errorCode = 0 Then GetOnWithIt()

where GetOnWithIt() is the function to be executed and uses variables xlFileNameToOpen & xlSheetNameToUse
the 2 variables are defined as follows in the Public Class theGUI
Public Shared xlFileNameToOpen As String
Public Shared xlSheetNameToUse As String

Thanks
Regards

JXB