Currently, in view_autoconfigure, the only condition for show_border
is !view_is_only_visible. view_is_only_visible does not cross the
boundary between the workspace's tiling and floating lists and does not
differentiate between them.
The result is, that in a workspace with zero or more tiling containers
and a single floating container, the floating container will lose its
borders as soon as it is split, provided that a only one view is visible
within the floating container.
Fixed by adjusting the condition for show_borders.
0cb9282aee