Toplevel::debug() is one of annoyances that you need to deal with when
implementing a new client type. It can be tempting to just write "this"
to the stream, but it will result in a crash.
In order to make implementing new client types easier, this change
introduces a debug stream insertion operator overload that works for all
kinds of the Toplevel class.
This change upstreams window hiding functionality from the XdgSurfaceClient
class to the WaylandClient class in order to reduce the amount of duplicated
code in new wayland client sub-classes.
Vlad Zahorodnii