When querying for an adjacent output we now need an absolute position in
order to know which adjacent output that matches. (The position is
either the current mouse position or the center of the currently focused
container, depending on context.)
If two outputs have one edge each that at least partially align with
each other they now count as adjacent.
Seamless mouse is affected by this and now properly moves and positions
itself between outputs with "uneven" placement (as long as they have at
least some part of the edge adjacent to each other).
When focusing or moving a container in a specified direction the center
of the current focused container decides where to look for an adjacent
output. So if e.g. an output has two adjacent outputs to the right and a
"focus right" command is issued then it's the placement of the currently
focused container that decides which output actually gets focused.
Also, if an output has at least one output adjacent in some direction
but the entire edge is not covered (ie. it has "holes" with no outputs),
then the algorithm will choose the output that is closest to the
currently focused container (this does not apply to seamless mouse, the
pointer will just stop at the edge in that case).
If e.g. a window has a popup open then that will lock the current focus,
making a workspace switch denied.
So don't move the mouse pointer in such cases.
In i3 the ipc reply will contain a human readable error message, and
this patch replicates that behaviour.
However, that error message is also useful for logging, which this
patch takes advantage of.
E.g. instead of logging errors directly in commands.c/checkargs, it is
fed back to the caller which eventually ends up logging everything with
maximum context available (config.c/read_config).
So instead of logging e.g. "Error on line 'exit'" it will now log:
"Error on line 'exit': Can't execute from config."
- replace visibilty mask integers with an enum
- set output's visibilty mask on creation
- added update_visibility to manually update a containers visibility (e.g. when it moved to an invisible workspace)
