Cannot open a new window from the gnome-shell overview when already open
tl;dr: I cannot open new window from the gnome-shell overview when gitg is already running, neither from the context menu on the app's icon on the dock, nor by using Shift+Return.
I use a workspace-per-project model, and often am working on more than one project at a time, which means I need to have multiple app windows open. For other apps, this is easily achieved by activating the gnome-shell overview using a keyboard shortcut, typing a few letters of the app's name, and pressing Shift+Enter. A new app window will be opened irrespective of whether the app is already running. Using the mouse, I'd right-click the app's icon on the dock and select New Window there.
Doing this gitg instead changes workspace and brings an existing gitg window forward, meaning I need to open a new window there, and then bring it over to the workspace I was on at the start. It's surprisingly disruptive! Right-clicking on the app's icon on the dock doesn't have a New Window option, either.
Cheers!