With applications comprising floating utility windows (GIMP, Inkscape, Pitivi, etc.), in gnome-shell's overview, when you drag the app's window to another workspaces, the utility windows don't follow.

You're then stuck with a bunch of orphans sitting on the current workspace that you can't easily move, unless you somehow manage to bring them to the front (if you've got no other windows obscuring them) and using shortcuts like ctrl+alt+shift+up/down.

Instead, transient utility windows and the like should follow their parent window that was moved to another workspace.