Checks for floating windows within the layout area and finds a maximum area
rectangle within that does not overlap with any of the floating windows.
This rectangle is used for all non-floating windows.
This new functionality introduced problems with the recommended configuration
of one of my other modules (X.A.FloatSnap.) A new and more reliable method of
distinguishing between clicks and drags where therefore introduced in the new
module X.A.AfterDrag.
This does not break any prior use of FloatSnap, but will require changes in
configuration if used together with AvoidFloats. (This is mentioned in the
docs for AvoidFloats and I recommend using the new configuration method even if
AvoidFloats is not in use.)
