The implementation works like this:
Containers can have a 'sticky-group' attribute. Imagine two different
containers (on two different workspaces) which have the same sticky-group.
Now you open a window in the first container. When you switch to the
other workspace, the window will be re-assigned to the other container.
An obvious problem which is not covered with the code at the moment is
having two containers with the same sticky-group visible at the same time.
This helps for windows which are immediately destroyed instead of
unmapped, like when starting i3status | ./foobar | dzen2 -dock
and foobar does not exist (i3status and dzen2 will get a SIGPIPE).
Before this commit, i3 used key bindings in SYNC mode for bindings
like Mode_switch + <a> and replayed the key if the current state
did not include Mode_switch. This had some problems:
1) The WM needed to acknowledge much more key presses than you
actually had bindings for, thus making the system a bit laggy
sometimes.
2) Users of layouts who constantly type in the third level (like
russian layouts) did not get their cyrillic symbols correctly
(they were not replayed right), neither did the keybindings
work in both modes.
So, the current implementation uses the following approach: XKB
provides an event which contains the current state (including
the current level). i3 signs up for this event and upon receival,
it re-maps the bindings using Mode_switch (enables them when the
level goes to the third level and disables them as soon as the
level goes back to normal). This fixes both problems.
