Default keybindings make a lot of sense, but Ctrl+Tab to switch tabs would be nice as well. Doesn't seem to work though.

Template generated with:
src/astroid/devel/get_keys.py > ~/.config/astroid/keybindings.orig

I've tried:
main_window.next_page=C-GDK_KEY_Tab # Next page, default: l, "b"
main_window.next_page=GDK_KEY_Tab # Next page, default: l, "b"
main_window.next_page= GDK_KEY_Tab" # Next page, default: l, "b"
main_window.next_page=l, GDK_KEY_Tab" # Next page, default: l, "b"
main_window.next_page=l, "GDK_KEY_Tab" # Next page, default: l, "b"
main_window.next_page=l, "C-GDK_KEY_Tab" # Next page, default: l, "b"
main_window.next_page=l, C-GDK_KEY_Tab # Next page, default: l, "b"
main_window.next_page=l,C-GDK_KEY_Tab # Next page, default: l, "b"

and none of them worked...