Comment 535 for bug 1218322

WORKAROUND on how to use keyboard Ctrl+Shift+/Alf+Shift+ shortcuts with Ctrl+Shift as layout switch.

Order of keys pressed for layout switching is important. So ['<Control>Shift_L'] implies Control pressed first and Shift pressed second. Inverse order won't work. You have to use ['<Shift>Control_L'] for inverse order.

On the other hand application shortcuts are order-independent, so you can use Ctrl+Shift+T or Shift+Ctrl+T in order to open new tab in Gnome Terminal. Once you're using Ctrl+Shift for layout switching it's still possible to use Shift+Ctrl+<whatever> for application shortcuts.

P.S.: Don't set switching keyboard layout with 'Ctrl+Shift' using XKB options. In this case you'll get order-independent layout switching, but all ways to invoke Ctrl+Shift+ shortcts will be broken.

P.P.S.: Take a note values of switch to next/previous input source are actually arrays(lists).
It's possible to set multiple key combinations i.e. I use: ['<Control>Shift_L', '<Shift>Shift_L'] and ['<Control>Shift_R', '<Shift>Shift_R'] respectively.