diff --git a/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/DelegatingFontPreferences.java b/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/DelegatingFontPreferences.java
index add18752ea7c..8a833bedd98c 100644
--- a/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/DelegatingFontPreferences.java
+++ b/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/DelegatingFontPreferences.java
@@ -20,7 +20,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.List;
 import java.util.function.Supplier;
 
-public class DelegatingFontPreferences implements FontPreferences {
+public class DelegatingFontPreferences extends FontPreferences {
   private Supplier<FontPreferences> myDelegateSupplier;
 
   public DelegatingFontPreferences(@NotNull Supplier<FontPreferences> delegateSupplier) {
diff --git a/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/FontPreferences.java b/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/FontPreferences.java
index bffdec3fa761..e04d7da3289f 100644
--- a/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/FontPreferences.java
+++ b/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/FontPreferences.java
@@ -22,36 +22,52 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.awt.*;
+import java.util.Collections;
 import java.util.List;
 
-public interface FontPreferences {
-  @NonNls @NotNull String DEFAULT_FONT_NAME = getDefaultFontName();
-  int DEFAULT_FONT_SIZE = FontSize.SMALL.getSize();
+public class FontPreferences {
+  public final static @NonNls @NotNull String DEFAULT_FONT_NAME = getDefaultFontName();
+  public final static int DEFAULT_FONT_SIZE = FontSize.SMALL.getSize();
 
-  float DEFAULT_LINE_SPACING = 1.0f;
-  String FALLBACK_FONT_FAMILY         = "Monospaced";
-  String MAC_OS_DEFAULT_FONT_FAMILY   = "Menlo";
-  String LINUX_DEFAULT_FONT_FAMILY    = "DejaVu Sans Mono";
-  String WINDOWS_DEFAULT_FONT_FAMILY  = FALLBACK_FONT_FAMILY;
+  public final static float DEFAULT_LINE_SPACING = 1.0f;
+  public final static String FALLBACK_FONT_FAMILY         = "Monospaced";
+  public final static String MAC_OS_DEFAULT_FONT_FAMILY   = "Menlo";
+  public final static String LINUX_DEFAULT_FONT_FAMILY    = "DejaVu Sans Mono";
+  public final static String WINDOWS_DEFAULT_FONT_FAMILY  = FALLBACK_FONT_FAMILY;
 
   @NotNull
-  List<String> getEffectiveFontFamilies();
+  public List<String> getEffectiveFontFamilies() {
+    return Collections.emptyList();
+  }
 
   @NotNull
-  List<String> getRealFontFamilies();
+  public List<String> getRealFontFamilies() {
+    return Collections.emptyList();
+  }
 
   @NotNull
-  String getFontFamily();
+  public String getFontFamily() {
+    return FALLBACK_FONT_FAMILY;
+  }
 
-  int getSize(@NotNull String fontFamily);
+  public int getSize(@NotNull String fontFamily) {
+    return DEFAULT_FONT_SIZE;
+  }
 
-  void copyTo(@NotNull FontPreferences preferences);
+  public void copyTo(@NotNull FontPreferences preferences) {
+  }
 
-  boolean useLigatures();
+  public boolean useLigatures() {
+    return false;
+  }
 
-  boolean hasSize(@NotNull String fontName);
+  public boolean hasSize(@NotNull String fontName) {
+    return false;
+  }
 
-  float getLineSpacing();
+  public float getLineSpacing() {
+    return DEFAULT_LINE_SPACING;
+  }
 
   /**
    * There is a possible case that particular font family is not available at particular environment (e.g. Monaco under *nix).
@@ -67,7 +83,7 @@ public interface FontPreferences {
    *                        <code>null</code> if font family with the given name is registered at the current environment
    */
   @Nullable
-  static String getFallbackName(@NotNull String fontName, int fontSize, @Nullable EditorColorsScheme fallbackScheme) {
+  public static String getFallbackName(@NotNull String fontName, int fontSize, @Nullable EditorColorsScheme fallbackScheme) {
     Font plainFont = new Font(fontName, Font.PLAIN, fontSize);
     if (plainFont.getFamily().equals("Dialog") && !("Dialog".equals(fontName) || fontName.startsWith("Dialog."))) {
       return fallbackScheme == null ? DEFAULT_FONT_NAME : fallbackScheme.getEditorFontName();
@@ -75,7 +91,7 @@ public interface FontPreferences {
     return null;
   }
 
-  static String getDefaultFontName() {
+  public static String getDefaultFontName() {
     if (SystemInfo.isWindows) return WINDOWS_DEFAULT_FONT_FAMILY;
     if (SystemInfo.isMacOSSnowLeopard) return MAC_OS_DEFAULT_FONT_FAMILY;
     if (SystemInfo.isXWindow && !GraphicsEnvironment.isHeadless()) {
diff --git a/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/ModifiableFontPreferences.java b/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/ModifiableFontPreferences.java
index 1fd6769596ed..3f807250f65e 100644
--- a/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/ModifiableFontPreferences.java
+++ b/platform/editor-ui-api/src/com/intellij/openapi/editor/colors/ModifiableFontPreferences.java
@@ -19,16 +19,16 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
 
-public interface ModifiableFontPreferences extends FontPreferences {
-  void clear();
-  void clearFonts();
-  void setUseLigatures(boolean useLigatures);
-  void addFontFamily(String family);
-  void register(String family, int size);
-  void setEffectiveFontFamilies(List<String> fontFamilies);
-  void setRealFontFamilies(List<String> fontFamilies);
-  void setTemplateFontSize(int size);
-  void setLineSpacing(float lineSpacing);
-  void resetFontSizes();
-  void setFontSize(@NotNull String fontFamily, int size);
+public abstract class ModifiableFontPreferences extends FontPreferences {
+  public abstract void clear();
+  public abstract void clearFonts();
+  public abstract void setUseLigatures(boolean useLigatures);
+  public abstract void addFontFamily(String family);
+  public abstract void register(String family, int size);
+  public abstract void setEffectiveFontFamilies(List<String> fontFamilies);
+  public abstract void setRealFontFamilies(List<String> fontFamilies);
+  public abstract void setTemplateFontSize(int size);
+  public abstract void setLineSpacing(float lineSpacing);
+  public abstract void resetFontSizes();
+  public abstract void setFontSize(@NotNull String fontFamily, int size);
 }
diff --git a/platform/editor-ui-ex/src/com/intellij/openapi/editor/colors/impl/FontPreferencesImpl.java b/platform/editor-ui-ex/src/com/intellij/openapi/editor/colors/impl/FontPreferencesImpl.java
index 0c5f2cf30c38..afa259d48e8b 100644
--- a/platform/editor-ui-ex/src/com/intellij/openapi/editor/colors/impl/FontPreferencesImpl.java
+++ b/platform/editor-ui-ex/src/com/intellij/openapi/editor/colors/impl/FontPreferencesImpl.java
@@ -36,7 +36,7 @@ import java.util.List;
  * @author Denis Zhdanov
  * @since 12/20/12 9:37 PM
  */
-public class FontPreferencesImpl implements ModifiableFontPreferences {
+public class FontPreferencesImpl extends ModifiableFontPreferences {
 
   @NotNull private final TObjectIntHashMap<String> myFontSizes    = new TObjectIntHashMap<>();
   @NotNull private final List<String> myEffectiveFontFamilies = ContainerUtilRt.newArrayList();