If you want to see the submodules in the bookmarks view you can do so quite easily, just open the submodule from the sidebar (double-click) and then use the menu option File > Bookmark Open Repositories. Anything that doesn't have a bookmark currently can be bookmarked, including the submodules.
I deliberately didn't make submodules appear in the bookmarks automatically because if they're just static dependencies they're just clutter. If you do modify your submodules a lot you can bookmark them selectively this way.
If you want to see the submodules in the bookmarks view you can do so quite easily, just open the submodule from the sidebar (double-click) and then use the menu option File > Bookmark Open Repositories. Anything that doesn't have a bookmark currently can be bookmarked, including the submodules.
I deliberately didn't make submodules appear in the bookmarks automatically because if they're just static dependencies they're just clutter. If you do modify your submodules a lot you can bookmark them selectively this way.