Ok, in that case you presented, the expected behaviour should be opening the "other form" in "Show mode" also, not allowing the edit. Anyway, blocking that specific button while in "show mode" is not available by Genio options or configurations, just through manual code entries, you have tags like FORM_CODEJS that you can use to do the trick.

Please avoid posting additional details to your original question as an answer post. It becomes confusing for other readers. Additional details can be added by editing the original question. Leaving a EDIT <date> line in your edit also helps avoid confusion.

Small one line details can be posted as a comments to a question that doesn't quite answer what you had in mind.