diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 80bdca6..d47a59b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -118,6 +118,7 @@ set(SOURCES
     anbox/graphics/layer_composer.cpp
     anbox/graphics/program_family.cpp
     anbox/graphics/primitives.h
+    anbox/graphics/renderer.h
 
     anbox/graphics/emugl/ColorBuffer.cpp
     anbox/graphics/emugl/DisplayManager.cpp
diff --git a/src/anbox/graphics/emugl/Renderable.cpp b/src/anbox/graphics/emugl/Renderable.cpp
index da32471..e75d1a2 100644
--- a/src/anbox/graphics/emugl/Renderable.cpp
+++ b/src/anbox/graphics/emugl/Renderable.cpp
@@ -47,3 +47,9 @@ void Renderable::set_screen_position(
     const anbox::graphics::Rect &screen_position) {
   screen_position_ = screen_position;
 }
+
+std::ostream &operator<<(std::ostream &out, const Renderable &r) {
+  return out << "{ name " << r.name() << " buffer " << r.buffer()
+             << " screen position " << r.screen_position() << " crop "
+             << r.crop() << " alpha " << r.alpha();
+}
diff --git a/src/anbox/graphics/emugl/Renderable.h b/src/anbox/graphics/emugl/Renderable.h
index bdf8a12..656b0b2 100644
--- a/src/anbox/graphics/emugl/Renderable.h
+++ b/src/anbox/graphics/emugl/Renderable.h
@@ -43,6 +43,16 @@ class Renderable {
 
   void set_screen_position(const anbox::graphics::Rect &screen_position);
 
+  inline bool operator==(const Renderable &rhs) const {
+    return (name_ == rhs.name() && buffer_ == rhs.buffer() &&
+            screen_position_ == rhs.screen_position() && crop_ == rhs.crop() &&
+            transformation_ == rhs.transformation() && alpha_ == rhs.alpha());
+  }
+
+  inline bool operator!=(const Renderable &rhs) const {
+    return !operator==(rhs);
+  }
+
  private:
   std::string name_;
   std::uint32_t buffer_;
@@ -52,6 +62,8 @@ class Renderable {
   float alpha_;
 };
 
+std::ostream &operator<<(std::ostream &out, const Renderable &r);
+
 typedef std::vector<Renderable> RenderableList;
 
 #endif
diff --git a/src/anbox/graphics/emugl/Renderer.h b/src/anbox/graphics/emugl/Renderer.h
index 973c8ae..5258639 100644
--- a/src/anbox/graphics/emugl/Renderer.h
+++ b/src/anbox/graphics/emugl/Renderer.h
@@ -27,6 +27,7 @@
 
 #include "anbox/graphics/primitives.h"
 #include "anbox/graphics/program_family.h"
+#include "anbox/graphics/renderer.h"
 
 #include <EGL/egl.h>
 
@@ -71,10 +72,10 @@ struct RendererWindow;
 // There is only one global instance, that can be retrieved with getFB(),
 // and which must be previously setup by calling initialize().
 //
-class Renderer {
+class Renderer : public anbox::graphics::Renderer {
  public:
   Renderer();
-  ~Renderer();
+  virtual ~Renderer();
 
   // Initialize the global instance.
   // |width| and |height| are the dimensions of the emulator GPU display
@@ -223,7 +224,7 @@ class Renderer {
 
   bool draw(EGLNativeWindowType native_window,
             const anbox::graphics::Rect& window_frame,
-            const RenderableList& renderables);
+            const RenderableList& renderables) override;
 
   // Return the host EGLDisplay used by this instance.
   EGLDisplay getDisplay() const { return m_eglDisplay; }
diff --git a/src/anbox/graphics/gl_renderer_server.cpp b/src/anbox/graphics/gl_renderer_server.cpp
index 24049aa..54ead08 100644
--- a/src/anbox/graphics/gl_renderer_server.cpp
+++ b/src/anbox/graphics/gl_renderer_server.cpp
@@ -43,10 +43,9 @@ void logger_write(const char *format, ...) {
 namespace anbox {
 namespace graphics {
 GLRendererServer::GLRendererServer(const std::shared_ptr<wm::Manager> &wm)
-    : renderer_(std::make_shared<Renderer>()),
+    : renderer_(std::make_shared<::Renderer>()),
       wm_(wm),
       composer_(std::make_shared<LayerComposer>(renderer_, wm)) {
-
   if (utils::is_env_set("USE_HOST_GLES")) {
     // Force the host EGL/GLES libraries as translator implementation
     ::setenv("ANDROID_EGL_LIB", "libEGL.so.1", 0);
@@ -83,8 +82,6 @@ GLRendererServer::GLRendererServer(const std::shared_ptr<wm::Manager> &wm)
   registerLayerComposer(composer_);
 }
 
-GLRendererServer::~GLRendererServer() {
-  renderer_->finalize();
-}
+GLRendererServer::~GLRendererServer() { renderer_->finalize(); }
 }  // namespace graphics
 }  // namespace anbox
diff --git a/src/anbox/graphics/layer_composer.cpp b/src/anbox/graphics/layer_composer.cpp
index 066779d..cdb5dfd 100644
--- a/src/anbox/graphics/layer_composer.cpp
+++ b/src/anbox/graphics/layer_composer.cpp
@@ -22,7 +22,8 @@
 
 namespace anbox {
 namespace graphics {
-LayerComposer::LayerComposer(const std::shared_ptr<Renderer> renderer, const std::shared_ptr<wm::Manager> &wm)
+LayerComposer::LayerComposer(const std::shared_ptr<Renderer> renderer,
+                             const std::shared_ptr<wm::Manager> &wm)
     : renderer_(renderer), wm_(wm) {}
 
 LayerComposer::~LayerComposer() {}
@@ -85,10 +86,9 @@ void LayerComposer::submit_layers(const RenderableList &renderables) {
       final_renderables.push_back(new_renderable);
     }
 
-    renderer_->draw(
-        window->native_handle(),
-        Rect{0, 0, window->frame().width(), window->frame().height()},
-        final_renderables);
+    renderer_->draw(window->native_handle(), Rect{0, 0, window->frame().width(),
+                                                  window->frame().height()},
+                    final_renderables);
   }
 }
 }  // namespace graphics
diff --git a/src/anbox/graphics/layer_composer.h b/src/anbox/graphics/layer_composer.h
index 3b8ded0..f71c351 100644
--- a/src/anbox/graphics/layer_composer.h
+++ b/src/anbox/graphics/layer_composer.h
@@ -18,12 +18,10 @@
 #ifndef ANBOX_GRAPHICS_LAYER_COMPOSER_H_
 #define ANBOX_GRAPHICS_LAYER_COMPOSER_H_
 
-#include "anbox/graphics/emugl/Renderable.h"
+#include "anbox/graphics/renderer.h"
 
 #include <memory>
 
-class Renderer;
-
 namespace anbox {
 namespace wm {
 class Manager;
@@ -31,7 +29,8 @@ class Manager;
 namespace graphics {
 class LayerComposer {
  public:
-  LayerComposer(const std::shared_ptr<Renderer> renderer, const std::shared_ptr<wm::Manager> &wm);
+  LayerComposer(const std::shared_ptr<Renderer> renderer,
+                const std::shared_ptr<wm::Manager> &wm);
   ~LayerComposer();
 
   void submit_layers(const RenderableList &renderables);
diff --git a/src/anbox/graphics/renderer.h b/src/anbox/graphics/renderer.h
new file mode 100644
index 0000000..74c91b1
--- /dev/null
+++ b/src/anbox/graphics/renderer.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2016 Simon Fels <morphis@gravedo.de>
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 3, as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranties of
+ * MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef ANBOX_GRAPHICS_RENDERER_H_
+#define ANBOX_GRAPHICS_RENDERER_H_
+
+#include "anbox/graphics/emugl/Renderable.h"
+
+#include <EGL/egl.h>
+
+namespace anbox {
+namespace graphics {
+class Renderer {
+ public:
+  virtual ~Renderer() {}
+
+  virtual bool draw(EGLNativeWindowType native_window,
+                    const anbox::graphics::Rect& window_frame,
+                    const RenderableList& renderables) = 0;
+};
+}  // namespace graphics
+}  // namespace anbox
+
+#endif
diff --git a/src/anbox/wm/default_platform_policy.cpp b/src/anbox/wm/default_platform_policy.cpp
index 8ab33b5..cfd11e4 100644
--- a/src/anbox/wm/default_platform_policy.cpp
+++ b/src/anbox/wm/default_platform_policy.cpp
@@ -24,7 +24,7 @@ class NullWindow : public anbox::wm::Window {
  public:
   NullWindow(const anbox::wm::Task::Id &task,
              const anbox::graphics::Rect &frame)
-      : anbox::wm::Window(nullptr, 0, frame) {}
+      : anbox::wm::Window(nullptr, task, frame) {}
 };
 }
 
@@ -34,7 +34,6 @@ DefaultPlatformPolicy::DefaultPlatformPolicy() {}
 
 std::shared_ptr<Window> DefaultPlatformPolicy::create_window(
     const anbox::wm::Task::Id &task, const anbox::graphics::Rect &frame) {
-  DEBUG("");
   return std::make_shared<::NullWindow>(task, frame);
 }
 }  // namespace wm
diff --git a/tests/anbox/graphics/CMakeLists.txt b/tests/anbox/graphics/CMakeLists.txt
index 8e7c8ad..85b07c2 100644
--- a/tests/anbox/graphics/CMakeLists.txt
+++ b/tests/anbox/graphics/CMakeLists.txt
@@ -1,2 +1,3 @@
 ANBOX_ADD_TEST(buffer_queue_tests buffer_queue_tests.cpp)
 ANBOX_ADD_TEST(buffered_io_stream_tests buffered_io_stream_tests.cpp)
+ANBOX_ADD_TEST(layer_composer_tests layer_composer_tests.cpp)
diff --git a/tests/anbox/graphics/layer_composer_tests.cpp b/tests/anbox/graphics/layer_composer_tests.cpp
new file mode 100644
index 0000000..c0eff82
--- /dev/null
+++ b/tests/anbox/graphics/layer_composer_tests.cpp
@@ -0,0 +1,225 @@
+/*
+ * Copyright (C) 2016 Simon Fels <morphis@gravedo.de>
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 3, as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranties of
+ * MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+// Both includes need to go first as otherwise they can conflict with EGL.h
+// being included by the following includes.
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "anbox/wm/default_platform_policy.h"
+#include "anbox/wm/manager.h"
+#include "anbox/wm/window_state.h"
+
+#include "anbox/graphics/layer_composer.h"
+
+using namespace ::testing;
+
+namespace {
+class MockRenderer : public anbox::graphics::Renderer {
+ public:
+  MOCK_METHOD3(draw, bool(EGLNativeWindowType, const anbox::graphics::Rect&,
+                          const RenderableList&));
+};
+}
+
+namespace anbox {
+namespace graphics {
+TEST(LayerComposer, FindsNoSuitableWindowForLayer) {
+  auto renderer = std::make_shared<MockRenderer>();
+
+  // The default policy will create a dumb window instance when requested
+  // from the manager.
+  auto platform_policy = std::make_shared<wm::DefaultPlatformPolicy>();
+  auto wm = std::make_shared<wm::Manager>(platform_policy);
+
+  auto single_window = wm::WindowState{
+      wm::Display::Id{1},
+      true,
+      graphics::Rect{0, 0, 1024, 768},
+      "org.anbox.test.1",
+      wm::Task::Id{1},
+      wm::Stack::Freeform,
+  };
+
+  wm->apply_window_state_update({single_window}, {});
+
+  LayerComposer composer(renderer, wm);
+
+  // A single renderable which has a different task id then the window we know
+  // about
+  RenderableList renderables = {
+      {"org.anbox.surface.2", 0, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+  };
+
+  // The renderer should not be called for a layer which doesn't exist
+  EXPECT_CALL(*renderer, draw(_, _, _)).Times(0);
+
+  composer.submit_layers(renderables);
+}
+
+TEST(LayerComposer, MapsLayersToWindows) {
+  auto renderer = std::make_shared<MockRenderer>();
+
+  // The default policy will create a dumb window instance when requested
+  // from the manager.
+  auto platform_policy = std::make_shared<wm::DefaultPlatformPolicy>();
+  auto wm = std::make_shared<wm::Manager>(platform_policy);
+
+  auto first_window = wm::WindowState{
+      wm::Display::Id{1},
+      true,
+      graphics::Rect{0, 0, 1024, 768},
+      "org.anbox.foo",
+      wm::Task::Id{1},
+      wm::Stack::Freeform,
+  };
+
+  auto second_window = wm::WindowState{
+      wm::Display::Id{1},
+      true,
+      graphics::Rect{300, 400, 1324, 1168},
+      "org.anbox.bar",
+      wm::Task::Id{2},
+      wm::Stack::Freeform,
+  };
+
+  wm->apply_window_state_update({first_window, second_window}, {});
+
+  LayerComposer composer(renderer, wm);
+
+  // A single renderable which has a different task id then the window we know
+  // about
+  RenderableList renderables = {
+      {"org.anbox.surface.1", 0, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+      {"org.anbox.surface.2", 1, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+  };
+
+  RenderableList first_window_renderables{
+      {"org.anbox.surface.1", 0, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+  };
+
+  RenderableList second_window_renderables{
+      {"org.anbox.surface.2", 1, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+  };
+
+  EXPECT_CALL(*renderer, draw(_, Rect{0, 0, first_window.frame().width(),
+                                      first_window.frame().height()},
+                              first_window_renderables))
+      .Times(1)
+      .WillOnce(Return(true));
+  EXPECT_CALL(*renderer, draw(_, Rect{0, 0, second_window.frame().width(),
+                                      second_window.frame().height()},
+                              second_window_renderables))
+      .Times(1)
+      .WillOnce(Return(true));
+
+  composer.submit_layers(renderables);
+}
+
+TEST(LayerComposer, WindowPartiallyOffscreen) {
+  auto renderer = std::make_shared<MockRenderer>();
+
+  // The default policy will create a dumb window instance when requested
+  // from the manager.
+  auto platform_policy = std::make_shared<wm::DefaultPlatformPolicy>();
+  auto wm = std::make_shared<wm::Manager>(platform_policy);
+
+  auto window = wm::WindowState{
+      wm::Display::Id{1},
+      true,
+      graphics::Rect{-100, -100, 924, 668},
+      "org.anbox.foo",
+      wm::Task::Id{1},
+      wm::Stack::Freeform,
+  };
+
+  wm->apply_window_state_update({window}, {});
+
+  LayerComposer composer(renderer, wm);
+
+  // Window is build out of two layers where one is placed inside the other
+  // but the layer covering the whole window is placed with its top left
+  // origin outside of the visible display area.
+  RenderableList renderables = {
+    {"org.anbox.surface.1", 0, {-100, -100, 924, 668}, {0, 0, 1024, 768}},
+    {"org.anbox.surface.1", 1, {0, 0, 100, 200}, {0, 0, 100, 200}},
+  };
+
+  RenderableList expected_renderables{
+    {"org.anbox.surface.1", 0, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+    {"org.anbox.surface.1", 1, {100, 100, 200, 300}, {0, 0, 100, 200}},
+  };
+
+  EXPECT_CALL(*renderer, draw(_, Rect{0, 0,
+                                      window.frame().width(),
+                                      window.frame().height()},
+                              expected_renderables))
+      .Times(1)
+      .WillOnce(Return(true));
+
+  composer.submit_layers(renderables);
+}
+
+TEST(LayerComposer, PopupShouldNotCauseWindowLayerOffset) {
+  auto renderer = std::make_shared<MockRenderer>();
+
+  // The default policy will create a dumb window instance when requested
+  // from the manager.
+  auto platform_policy = std::make_shared<wm::DefaultPlatformPolicy>();
+  auto wm = std::make_shared<wm::Manager>(platform_policy);
+
+  auto window = wm::WindowState{
+      wm::Display::Id{1},
+      true,
+      graphics::Rect{1120, 270, 2144, 1038},
+      "org.anbox.foo",
+      wm::Task::Id{3},
+      wm::Stack::Freeform,
+  };
+
+  wm->apply_window_state_update({window}, {});
+
+  LayerComposer composer(renderer, wm);
+
+  // Having two renderables where the second smaller one overlaps the bigger
+  // one and goes a bit offscreen. This should be still placed correctly and
+  // the small layer should go offscreen as it is supposed to. This typically
+  // happens when a popup window appears which has a shadow attached which goes
+  // out of the window area. In our case this is not possible as the area the
+  // window has available is static.
+  RenderableList renderables = {
+    {"org.anbox.surface.3", 0, {1120,270,2144,1038}, {0, 0, 1024, 768}},
+    {"org.anbox.surface.3", 1, {1904, 246, 2164, 406}, {0, 0, 260, 160}},
+  };
+
+  RenderableList expected_renderables{
+    {"org.anbox.surface.3", 0, {0, 0, 1024, 768}, {0, 0, 1024, 768}},
+    {"org.anbox.surface.3", 1, {784, -24, 1044, 136}, {0, 0, 260, 160}},
+  };
+
+  EXPECT_CALL(*renderer, draw(_, Rect{0, 0,
+                                      window.frame().width(),
+                                      window.frame().height()},
+                              expected_renderables))
+      .Times(1)
+      .WillOnce(Return(true));
+
+  composer.submit_layers(renderables);
+}
+
+}  // namespace graphics
+}  // namespace anbox