How to (re)load a form in a sidebar panel?

I have created an app to upload and share large files over the network. Instead of sending attachments, files are being stored in a central repository and references to the containing document are being sent.

It works great, users select recipients, add a message and select and upload a file. File size is being checked via this procedure. Recipients receive a separate download URL and access code. The web interface is based upon the XPages framework.

To make it easier to create new documents the idea came up to provide the upload form in a  sidebar panel.

Not a problem, you would say but somehow. But then I am faced with the following question: how do I ‘reload’ the form in the panel?  The

@Command([Compose]; “”; “FormA”)

opens the form in a normal window pane (not within the sidebar panel window pane).

A similar attempt:

Sub Click(Source As Button)
Dim workspace As New NotesUIWorkspace
Call workspace.ComposeDocument( “”, “”, “FormB” )
End Sub

has the same effect.

And with

Sub Click(Source As Button)
Dim ws As New NotesUIWorkspace
Dim ses As New NotesSession
Dim doc As NotesDocument
Dim uidoc As NotesUIDocument
Set uidoc = ws.CurrentDocument
Call uidoc.Close
Set doc = New NotesDocument( ses.CurrentDatabase )
doc.form = “FormA”
Call ws.EditDocument(True, doc)
End Sub

I get the message:

Do you got any suggestions?