Comment 187 for bug 1245473

I believe the most serious objection with this request is that it violates the XKB specification (see the description of SA_LockGroup in section 6.3 of "The X Keyboard Extension: Protocol Specification").

In the same specification, in section 4.0 of appendix D ("Protocol Encoding"), we see in the description of SA_LockGroup that there are still 5 unused bits in the flags field. My proposal in to use one of these bits decide whether to lock groups on press or release. By default (bit is zero), lock groups on press as the protocol specification demands. If the flag is one, lock groups on release. So by default, we would conform to the specification, and add the alternative behaviour as a new possibility beyond the specification.

There are some usage implications. One must use 'Private' do create actions with the new flag set (until xkbcomp is updated as well), and one needs support in xkeyboard-config to make the new feature usable for non-XKB-hackers.