diff --git a/src/filter_registry.cc b/src/filter_registry.cc
index 208adaa3..c9f9149a 100644
--- a/src/filter_registry.cc
+++ b/src/filter_registry.cc
@@ -1,6 +1,7 @@
 #include "filter_registry.hh"
 
 #include "exception.hh"
+#include "window.hh"
 
 namespace Kakoune
 {
@@ -17,14 +18,15 @@ void FilterRegistry::register_factory(const std::string& name,
     m_factories[name] = factory;
 }
 
-FilterAndId FilterRegistry::get_filter(const std::string& name,
-                                       const FilterParameters& parameters)
+void FilterRegistry::add_filter_to_window(Window& window,
+                                          const std::string& name,
+                                          const FilterParameters& parameters)
 {
     auto it = m_factories.find(name);
     if (it == m_factories.end())
         throw factory_not_found();
 
-    return it->second(parameters);
+    window.add_filter(it->second(window, parameters));
 }
 
 }
diff --git a/src/filter_registry.hh b/src/filter_registry.hh
index 09b1fec2..fef04822 100644
--- a/src/filter_registry.hh
+++ b/src/filter_registry.hh
@@ -10,9 +10,12 @@
 namespace Kakoune
 {
 
+class Window;
+
 typedef std::vector<std::string> FilterParameters;
 
-typedef std::function<FilterAndId (const FilterParameters& params)> FilterFactory;
+typedef std::function<FilterAndId (Window& window,
+                                   const FilterParameters& params)> FilterFactory;
 
 class FilterRegistry : public Singleton<FilterRegistry>
 {
@@ -20,8 +23,9 @@ public:
     void register_factory(const std::string& name,
                           const FilterFactory& factory);
 
-    FilterAndId get_filter(const std::string& factory_name,
-                           const FilterParameters& parameters);
+    void add_filter_to_window(Window& window,
+                              const std::string& factory_name,
+                              const FilterParameters& parameters);
 
 private:
     std::unordered_map<std::string, FilterFactory> m_factories;
diff --git a/src/filters.cc b/src/filters.cc
index 6d9e99fb..130a9066 100644
--- a/src/filters.cc
+++ b/src/filters.cc
@@ -1,5 +1,6 @@
 #include "filters.hh"
 
+#include "window.hh"
 #include "display_buffer.hh"
 #include "filter_registry.hh"
 #include <boost/regex.hpp>
@@ -139,7 +140,8 @@ class SimpleFilterFactory
 public:
     SimpleFilterFactory(const std::string& id) : m_id(id) {}
 
-    FilterAndId operator()(const FilterParameters& params) const
+    FilterAndId operator()(Window& window,
+                           const FilterParameters& params) const
     {
         return FilterAndId(m_id, FilterFunc(filter_func));
     }
@@ -147,12 +149,89 @@ private:
     std::string m_id;
 };
 
+class SelectionsHighlighter
+{
+public:
+    SelectionsHighlighter(Window& window)
+        : m_window(window)
+    {
+    }
+
+    void operator()(DisplayBuffer& display_buffer)
+    {
+        SelectionList sorted_selections = m_window.selections();
+
+        std::sort(sorted_selections.begin(), sorted_selections.end(),
+                  [](const Selection& lhs, const Selection& rhs) { return lhs.begin() < rhs.begin(); });
+
+        auto atom_it = display_buffer.begin();
+        auto sel_it = sorted_selections.begin();
+
+        while (atom_it != display_buffer.end()
+               and sel_it != sorted_selections.end())
+        {
+            Selection& sel = *sel_it;
+            DisplayAtom& atom = *atom_it;
+
+            // [###------]
+            if (atom.begin() >= sel.begin() and atom.begin() < sel.end() and atom.end() > sel.end())
+            {
+                atom_it = display_buffer.split(atom_it, sel.end());
+                atom_it->attribute() |= Attributes::Underline;
+                ++atom_it;
+                ++sel_it;
+            }
+            // [---###---]
+            else if (atom.begin() < sel.begin() and atom.end() > sel.end())
+            {
+                atom_it = display_buffer.split(atom_it, sel.begin());
+                atom_it = display_buffer.split(++atom_it, sel.end());
+                atom_it->attribute() |= Attributes::Underline;
+                ++atom_it;
+                ++sel_it;
+            }
+            // [------###]
+            else if (atom.begin() < sel.begin() and atom.end() > sel.begin())
+            {
+                atom_it = ++display_buffer.split(atom_it, sel.begin());
+                atom_it->attribute() |= Attributes::Underline;
+                ++atom_it;
+            }
+            // [#########]
+            else if (atom.begin() >= sel.begin() and atom.end() <= sel.end())
+            {
+                atom_it->attribute() |= Attributes::Underline;
+                ++atom_it;
+            }
+            // [---------]
+            else if (atom.begin() >= sel.end())
+                ++sel_it;
+            // [---------]
+            else if (atom.end() <= sel.begin())
+                ++atom_it;
+            else
+                assert(false);
+        }
+    }
+
+    static FilterAndId create(Window& window,
+                              const FilterParameters& params)
+    {
+        return FilterAndId("highlight_selections",
+                            SelectionsHighlighter(window));
+    }
+
+private:
+    const Window& m_window;
+};
+
 void register_filters()
 {
     FilterRegistry& registry = FilterRegistry::instance();
     
+    registry.register_factory("highlight_selections", SelectionsHighlighter::create);
     registry.register_factory("expand_tabs", SimpleFilterFactory<expand_tabulations>("expand_tabs"));
-    registry.register_factory("line_numbers", SimpleFilterFactory<show_line_numbers>("line_numbers"));
+    registry.register_factory("number_lines", SimpleFilterFactory<show_line_numbers>("number_lines"));
     registry.register_factory("hlcpp", SimpleFilterFactory<colorize_cplusplus>("hlcpp"));
 }
 
diff --git a/src/main.cc b/src/main.cc
index 81442cd4..5b6c4351 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -441,8 +441,8 @@ void add_filter(const CommandParameters& params)
     {
         FilterRegistry& registry = FilterRegistry::instance();
         FilterParameters filter_params(params.begin()+1, params.end());
-        FilterAndId filter_and_id = registry.get_filter(params[0], filter_params);
-        current_window->add_filter(std::move(filter_and_id));
+        registry.add_filter_to_window(*current_window, params[0],
+                                      filter_params);
     }
     catch (runtime_error& err)
     {
diff --git a/src/window.cc b/src/window.cc
index 4b0fdd5f..c0ecdc28 100644
--- a/src/window.cc
+++ b/src/window.cc
@@ -38,75 +38,6 @@ private:
     Buffer& m_buffer;
 };
 
-class HighlightSelections
-{
-public:
-    HighlightSelections(Window& window)
-        : m_window(window)
-    {
-    }
-
-    void operator()(DisplayBuffer& display_buffer)
-    {
-        SelectionList sorted_selections = m_window.m_selections;
-
-        std::sort(sorted_selections.begin(), sorted_selections.end(),
-                  [](const Selection& lhs, const Selection& rhs) { return lhs.begin() < rhs.begin(); });
-
-        auto atom_it = display_buffer.begin();
-        auto sel_it = sorted_selections.begin();
-
-        while (atom_it != display_buffer.end()
-               and sel_it != sorted_selections.end())
-        {
-            Selection& sel = *sel_it;
-            DisplayAtom& atom = *atom_it;
-
-            // [###------]
-            if (atom.begin() >= sel.begin() and atom.begin() < sel.end() and atom.end() > sel.end())
-            {
-                atom_it = display_buffer.split(atom_it, sel.end());
-                atom_it->attribute() |= Attributes::Underline;
-                ++atom_it;
-                ++sel_it;
-            }
-            // [---###---]
-            else if (atom.begin() < sel.begin() and atom.end() > sel.end())
-            {
-                atom_it = display_buffer.split(atom_it, sel.begin());
-                atom_it = display_buffer.split(++atom_it, sel.end());
-                atom_it->attribute() |= Attributes::Underline;
-                ++atom_it;
-                ++sel_it;
-            }
-            // [------###]
-            else if (atom.begin() < sel.begin() and atom.end() > sel.begin())
-            {
-                atom_it = ++display_buffer.split(atom_it, sel.begin());
-                atom_it->attribute() |= Attributes::Underline;
-                ++atom_it;
-            }
-            // [#########]
-            else if (atom.begin() >= sel.begin() and atom.end() <= sel.end())
-            {
-                atom_it->attribute() |= Attributes::Underline;
-                ++atom_it;
-            }
-            // [---------]
-            else if (atom.begin() >= sel.end())
-                ++sel_it;
-            // [---------]
-            else if (atom.end() <= sel.begin())
-                ++atom_it;
-            else
-                assert(false);
-        }
-    }
-
-private:
-    const Window& m_window;
-};
-
 Window::Window(Buffer& buffer)
     : m_buffer(buffer),
       m_position(0, 0),
@@ -116,9 +47,9 @@ Window::Window(Buffer& buffer)
     m_selections.push_back(Selection(buffer.begin(), buffer.begin()));
 
     FilterRegistry& registry = FilterRegistry::instance();
-    add_filter(registry.get_filter("expand_tabs", FilterParameters()));
-    add_filter(FilterAndId("show_selections", HighlightSelections(*this)));
-    add_filter(registry.get_filter("hlcpp", FilterParameters()));
+    registry.add_filter_to_window(*this, "expand_tabs", FilterParameters());
+    registry.add_filter_to_window(*this, "highlight_selections", FilterParameters());
+    registry.add_filter_to_window(*this, "hlcpp", FilterParameters());
 }
 
 void Window::check_invariant() const
diff --git a/src/window.hh b/src/window.hh
index 12003c6a..9d0de609 100644
--- a/src/window.hh
+++ b/src/window.hh
@@ -58,6 +58,7 @@ public:
     void clear_selections();
     void select(const Selector& selector, bool append = false);
     BufferString selection_content() const;
+    const SelectionList selections() const { return m_selections; }
 
     void set_dimensions(const DisplayCoord& dimensions);
 
@@ -95,8 +96,6 @@ private:
     friend class IncrementalInserter;
     IncrementalInserter* m_current_inserter;
 
-    friend class HighlightSelections;
-
     Buffer&       m_buffer;
     BufferCoord   m_position;
     DisplayCoord  m_dimensions;