How to keep focus on textbox when opening a browser or another app from an action

Hi.

We have an app (in VB .net) where a user uses Dragon to enter text (voice to text) in a specific textbox. The problem is that we have a button that has the action to open a browser window and the user loses focus from the box.

Is there a way to keep the focus on said textbox when opening the other app? So that the user continue using dictation without having to go back with a mouse.

Thanks en advance!