diff --git a/repos/gems/include/gems/local_reporter.h b/repos/gems/include/gems/local_reporter.h
index 2f54102c02..75268fcaa0 100644
--- a/repos/gems/include/gems/local_reporter.h
+++ b/repos/gems/include/gems/local_reporter.h
@@ -19,33 +19,40 @@
 #include <util/xml_generator.h>
 #include <report_session/client.h>
 
-struct Local_reporter
+class Local_reporter
 {
-	Report::Session_client _session;
+	private:
 
-	Genode::Attached_dataspace _ds;
+		Local_reporter(Local_reporter const &);
+		Local_reporter &operator = (Local_reporter const &);
 
-	char const *_name;
+		Report::Session_client _session;
 
-	Local_reporter(Genode::Region_map &rm, char const *name,
-	               Genode::Capability<Report::Session> session_cap)
-	:
-		_session(session_cap), _ds(rm, _session.dataspace()), _name(name)
-	{ }
+		Genode::Attached_dataspace _ds;
 
-	struct Xml_generator : public Genode::Xml_generator
-	{
-		template <typename FUNC>
-		Xml_generator(Local_reporter &reporter, FUNC const &func)
+		char const *_name;
+
+	public:
+
+		Local_reporter(Genode::Region_map &rm, char const *name,
+		               Genode::Capability<Report::Session> session_cap)
 		:
-			Genode::Xml_generator(reporter._ds.local_addr<char>(),
-			                      reporter._ds.size(),
-			                      reporter._name,
-			                      func)
+			_session(session_cap), _ds(rm, _session.dataspace()), _name(name)
+		{ }
+
+		struct Xml_generator : public Genode::Xml_generator
 		{
-			reporter._session.submit(used());
-		}
-	};
+			template <typename FUNC>
+			Xml_generator(Local_reporter &reporter, FUNC const &func)
+			:
+				Genode::Xml_generator(reporter._ds.local_addr<char>(),
+				                      reporter._ds.size(),
+				                      reporter._name,
+				                      func)
+			{
+				reporter._session.submit(used());
+			}
+		};
 };
 
 #endif /* _INCLUDE__GEMS__LOCAL_REPORTER_H_ */
diff --git a/repos/gems/src/server/wm/decorator_nitpicker.h b/repos/gems/src/server/wm/decorator_nitpicker.h
index 34f7cc146e..b04367594c 100644
--- a/repos/gems/src/server/wm/decorator_nitpicker.h
+++ b/repos/gems/src/server/wm/decorator_nitpicker.h
@@ -36,6 +36,7 @@ namespace Wm { class Main;
 	using Genode::Attached_ram_dataspace;
 	using Genode::Signal_handler;
 	using Genode::Reporter;
+	using Genode::Interface;
 }
 
 
@@ -47,7 +48,7 @@ namespace Wm {
 }
 
 
-struct Wm::Decorator_content_callback
+struct Wm::Decorator_content_callback : Interface
 {
 	virtual void content_geometry(Window_registry::Id win_id, Rect rect) = 0;
 
@@ -81,7 +82,7 @@ class Wm::Decorator_content_registry
 			{ }
 		};
 
-		List<Entry>  _list;
+		List<Entry>  _list { };
 		Allocator   &_entry_alloc;
 
 		Entry const &_lookup(Nitpicker::Session::View_handle view_handle) const
@@ -149,8 +150,11 @@ class Wm::Decorator_content_registry
 
 
 struct Wm::Decorator_nitpicker_session : Genode::Rpc_object<Nitpicker::Session>,
-                                         List<Decorator_nitpicker_session>::Element
+                                         private List<Decorator_nitpicker_session>::Element
 {
+	friend class List<Decorator_nitpicker_session>;
+	using List<Decorator_nitpicker_session>::Element::next;
+
 	typedef Nitpicker::View_capability      View_capability;
 	typedef Nitpicker::Session::View_handle View_handle;
 
@@ -162,7 +166,7 @@ struct Wm::Decorator_nitpicker_session : Genode::Rpc_object<Nitpicker::Session>,
 
 	Nitpicker::Connection _nitpicker_session { _env, "decorator" };
 
-	Genode::Signal_context_capability _mode_sigh;
+	Genode::Signal_context_capability _mode_sigh { };
 
 	typedef Nitpicker::Session::Command_buffer Command_buffer;
 
diff --git a/repos/gems/src/server/wm/layouter_nitpicker.h b/repos/gems/src/server/wm/layouter_nitpicker.h
index 9659670ee9..59f12ee191 100644
--- a/repos/gems/src/server/wm/layouter_nitpicker.h
+++ b/repos/gems/src/server/wm/layouter_nitpicker.h
@@ -37,7 +37,7 @@ struct Wm::Layouter_nitpicker_session : Genode::Rpc_object<Nitpicker::Session>
 	 */
 	Nitpicker::Connection _mode_sigh_nitpicker;
 
-	Genode::Signal_context_capability _mode_sigh;
+	Genode::Signal_context_capability _mode_sigh { };
 
 	Attached_ram_dataspace _command_ds;
 
diff --git a/repos/gems/src/server/wm/nitpicker.h b/repos/gems/src/server/wm/nitpicker.h
index 660bf47ba4..e3d79bf0ee 100644
--- a/repos/gems/src/server/wm/nitpicker.h
+++ b/repos/gems/src/server/wm/nitpicker.h
@@ -51,6 +51,7 @@ namespace Wm {
 	using Genode::Signal_transmitter;
 	using Genode::Reporter;
 	using Genode::Capability;
+	using Genode::Interface;
 }
 
 namespace Wm { namespace Nitpicker {
@@ -81,19 +82,24 @@ namespace Wm { namespace Nitpicker {
  * clicks into an already focused window should be of no interest to the
  * layouter. So we hide them from the layouter.
  */
-struct Wm::Nitpicker::Click_handler
+struct Wm::Nitpicker::Click_handler : Interface
 {
 	virtual void handle_click(Point pos) = 0;
 	virtual void handle_enter(Point pos) = 0;
 };
 
 
-struct Nitpicker::View { GENODE_RPC_INTERFACE(); };
+struct Nitpicker::View : Genode::Interface { GENODE_RPC_INTERFACE(); };
 
 
-class Wm::Nitpicker::View : public Genode::Weak_object<View>,
+class Wm::Nitpicker::View : private Genode::Weak_object<View>,
                             public Genode::Rpc_object< ::Nitpicker::View>
 {
+	private:
+
+		friend class Genode::Weak_ptr<View>;
+		friend class Genode::Locked_ptr<View>;
+
 	protected:
 
 		typedef Genode::String<100>             Title;
@@ -102,12 +108,12 @@ class Wm::Nitpicker::View : public Genode::Weak_object<View>,
 
 		Session_label              _session_label;
 		Nitpicker::Session_client &_real_nitpicker;
-		View_handle                _real_handle;
-		Title                      _title;
-		Rect                       _geometry;
-		Point                      _buffer_offset;
-		Weak_ptr<View>             _neighbor_ptr;
-		bool                       _neighbor_behind;
+		View_handle                _real_handle     { };
+		Title                      _title           { };
+		Rect                       _geometry        { };
+		Point                      _buffer_offset   { };
+		Weak_ptr<View>             _neighbor_ptr    { };
+		bool                       _neighbor_behind { };
 		bool                       _has_alpha;
 
 		View(Nitpicker::Session_client &real_nitpicker,
@@ -165,6 +171,9 @@ class Wm::Nitpicker::View : public Genode::Weak_object<View>,
 				_real_nitpicker.destroy_view(_real_handle);
 		}
 
+		using Genode::Weak_object<View>::weak_ptr;
+		using Genode::Weak_object<View>::lock_for_destruction;
+
 		Point virtual_position() const { return _geometry.p1(); }
 
 		virtual bool belongs_to_win_id(Window_registry::Id id) const = 0;
@@ -194,7 +203,7 @@ class Wm::Nitpicker::View : public Genode::Weak_object<View>,
 
 		virtual Point input_anchor_position() const = 0;
 
-		virtual void stack(Weak_ptr<View> neighbor_ptr, bool behind) { }
+		virtual void stack(Weak_ptr<View>, bool) { }
 
 		View_handle real_handle() const { return _real_handle; }
 
@@ -218,11 +227,13 @@ class Wm::Nitpicker::View : public Genode::Weak_object<View>,
 
 
 class Wm::Nitpicker::Top_level_view : public View,
-                                      public List<Top_level_view>::Element
+                                      private List<Top_level_view>::Element
 {
 	private:
 
-		Window_registry::Id _win_id;
+		friend class List<Top_level_view>;
+
+		Window_registry::Id _win_id { };
 
 		Window_registry &_window_registry;
 
@@ -230,11 +241,11 @@ class Wm::Nitpicker::Top_level_view : public View,
 		 * Geometry of window-content view, which corresponds to the location
 		 * of the window content as known by the decorator.
 		 */
-		Rect _content_geometry;
+		Rect _content_geometry { };
 
 		bool _resizeable = false;
 
-		Title         _window_title;
+		Title         _window_title { };
 		Session_label _session_label;
 
 		typedef Nitpicker::Session::Command Command;
@@ -259,6 +270,8 @@ class Wm::Nitpicker::Top_level_view : public View,
 			View::lock_for_destruction();
 		}
 
+		using List<Top_level_view>::Element::next;
+
 		void _propagate_view_geometry() override { }
 
 		void geometry(Rect geometry) override
@@ -337,10 +350,12 @@ class Wm::Nitpicker::Top_level_view : public View,
 
 
 class Wm::Nitpicker::Child_view : public View,
-                                  public List<Child_view>::Element
+                                  private List<Child_view>::Element
 {
 	private:
 
+		friend class List<Child_view>;
+
 		Weak_ptr<View> mutable _parent;
 
 	public:
@@ -360,6 +375,8 @@ class Wm::Nitpicker::Child_view : public View,
 			View::lock_for_destruction();
 		}
 
+		using List<Child_view>::Element::next;
+
 		void _propagate_view_geometry() override
 		{
 			_real_nitpicker.enqueue<Command::Geometry>(_real_handle, _geometry);
@@ -418,7 +435,7 @@ class Wm::Nitpicker::Child_view : public View,
 };
 
 
-struct Wm::Nitpicker::Session_control_fn
+struct Wm::Nitpicker::Session_control_fn : Interface
 {
 	virtual void session_control(char const *selector, Session::Session_control) = 0;
 	
@@ -426,10 +443,12 @@ struct Wm::Nitpicker::Session_control_fn
 
 
 class Wm::Nitpicker::Session_component : public Rpc_object<Nitpicker::Session>,
-                                         public List<Session_component>::Element
+                                         private List<Session_component>::Element
 {
 	private:
 
+		friend class List<Session_component>;
+
 		typedef Nitpicker::Session::View_handle View_handle;
 
 		Genode::Env &_env;
@@ -442,13 +461,13 @@ class Wm::Nitpicker::Session_component : public Rpc_object<Nitpicker::Session>,
 		Session_control_fn          &_session_control_fn;
 		Tslab<Top_level_view, 4000>  _top_level_view_alloc;
 		Tslab<Child_view, 4000>      _child_view_alloc;
-		List<Top_level_view>         _top_level_views;
-		List<Child_view>             _child_views;
+		List<Top_level_view>         _top_level_views { };
+		List<Child_view>             _child_views { };
 		Input::Session_component     _input_session { _env, _ram };
 		Input::Session_capability    _input_session_cap;
 		Click_handler               &_click_handler;
-		Signal_context_capability    _mode_sigh;
-		Area                         _requested_size;
+		Signal_context_capability    _mode_sigh { };
+		Area                         _requested_size { };
 		bool                         _resize_requested = false;
 		bool                         _has_alpha = false;
 		Point                  const _initial_pointer_pos { -1, -1 };
@@ -744,6 +763,8 @@ class Wm::Nitpicker::Session_component : public Rpc_object<Nitpicker::Session>,
 			_env.ep().dissolve(_input_session);
 		}
 
+		using List<Session_component>::Element::next;
+
 		void upgrade(char const *args)
 		{
 			size_t const ram_quota = Arg_string::find_arg(args, "ram_quota").ulong_value(0);
@@ -986,6 +1007,12 @@ class Wm::Nitpicker::Root : public Genode::Rpc_object<Genode::Typed_root<Session
 {
 	private:
 
+		/**
+		 * Noncopyable
+		 */
+		Root(Root const &);
+		Root &operator = (Root const &);
+
 		Genode::Env &_env;
 
 		Genode::Attached_rom_dataspace _config { _env, "config" };
@@ -1064,11 +1091,11 @@ class Wm::Nitpicker::Root : public Genode::Rpc_object<Genode::Typed_root<Session
 		/**
 		 * List of regular sessions
 		 */
-		List<Session_component> _sessions;
+		List<Session_component> _sessions { };
 
 		Layouter_nitpicker_session *_layouter_session = nullptr;
 
-		List<Decorator_nitpicker_session> _decorator_sessions;
+		List<Decorator_nitpicker_session> _decorator_sessions { };
 
 		/**
 		 * Nitpicker session used to perform session-control operations
@@ -1104,7 +1131,7 @@ class Wm::Nitpicker::Root : public Genode::Rpc_object<Genode::Typed_root<Session
 		 ********************/
 
 		Genode::Session_capability session(Session_args const &args,
-		                                   Affinity     const &affinity) override
+		                                   Affinity     const &) override
 		{
 			Genode::Session_label const session_label =
 				Genode::label_from_args(args.string());
diff --git a/repos/gems/src/server/wm/target.mk b/repos/gems/src/server/wm/target.mk
index 08fae55d85..6626626237 100644
--- a/repos/gems/src/server/wm/target.mk
+++ b/repos/gems/src/server/wm/target.mk
@@ -2,5 +2,3 @@ TARGET   = wm
 SRC_CC   = main.cc
 LIBS     = base
 INC_DIR += $(PRG_DIR)
-
-CC_CXX_WARN_STRICT =
diff --git a/repos/gems/src/server/wm/window_registry.h b/repos/gems/src/server/wm/window_registry.h
index 544014b75c..10465726e9 100644
--- a/repos/gems/src/server/wm/window_registry.h
+++ b/repos/gems/src/server/wm/window_registry.h
@@ -76,9 +76,9 @@ class Wm::Window_registry
 
 				struct Attr
 				{
-					Title         title;
-					Session_label label;
-					Area          size;
+					Title         title { };
+					Session_label label { };
+					Area          size  { };
 					Has_alpha     has_alpha = HAS_NO_ALPHA;
 					Hidden        hidden = NOT_HIDDEN;
 					Resizeable    resizeable = NOT_RESIZEABLE;
@@ -94,8 +94,8 @@ class Wm::Window_registry
 					}
 				};
 
-				Attr         _attr;
-				Attr mutable _flushed_attr;
+				Attr         _attr { };
+				Attr mutable _flushed_attr { };
 
 				friend class Window_registry;
 
@@ -164,9 +164,9 @@ class Wm::Window_registry
 
 		enum { MAX_WINDOWS = 1024 };
 
-		Genode::Bit_allocator<MAX_WINDOWS> _window_ids;
+		Genode::Bit_allocator<MAX_WINDOWS> _window_ids { };
 
-		List<Window> _windows;
+		List<Window> _windows { };
 
 		Window *_lookup(Id id)
 		{