Santiago: I'm not sure about your definition of "just some corner cases" - keyboard layout switching using only shift keys has been the norm since forever, even on X, and dismissing basically all multi-lingual users as "just some corner cases" is not productive.
XKB handles the requirement of using only shift keys for layout changes, and if you intend to drop that, please provide an alternative that meets the requirements.
Personally I've been using ALT-SPACE as a layout shortcut on some operating systems (mainly as a workaround for missing patch for XKB bug #865) and it is painful.
Santiago: I'm not sure about your definition of "just some corner cases" - keyboard layout switching using only shift keys has been the norm since forever, even on X, and dismissing basically all multi-lingual users as "just some corner cases" is not productive.
XKB handles the requirement of using only shift keys for layout changes, and if you intend to drop that, please provide an alternative that meets the requirements.
Personally I've been using ALT-SPACE as a layout shortcut on some operating systems (mainly as a workaround for missing patch for XKB bug #865) and it is painful.