Does anyone know where this application is located and what its package name is?
I have googled for it and not found it using the name alone which is all i have at the moment.
Thanks in advance.
Banner Designer is part of GNOME Software. The package is "gnome-software"
From a terminal you can run gnome-software-editor
It was introduced as part of this commit.
Banner Designer is used to create the application specific info panes (Click on an application) you see in GNOME Software.
As the commit says, an appdeveloper can open their applications appstream file; they can format, add colours etc using CSS before saving it out in appstream format again.
GNOME Software reads an applications appstream file and displays that to the end-user.