I have tried setting a custom lister named "horizontal" in both the tray and startup dialogs but it never launches that way. I can launch it from the task bar context menu or from a shortcut with the lister name as a switch but not by clicking direcly on the DO startmenu or taskbar icon.
Save it as your actual default lister (Settings > Set As Default Lister) if it's what you want to open whenever a new window is opened via any method.
(Then also reset both settings in the screenshot to open the default lister, to keep things simple.)
The "taskbar icon" setting means the "tray icon", not the main part of the taskbar which will launch Opus if it isn't already running, and otherwise opens a default lister if Opus is already running in the background but has no windows open.
Ok. Thanks. I have one last question that I will put in a new thread, so others can see subject matter.