Autocomplete on space bar and undo on delete (#1179)

* Refactor: Implement the space key as an editing action

The space key is no longer a CHAR key but now an EDITING key. This
allows changing the behavior of the space bar while allowing custom
layout users to define a key outputing a space as before.

KeyModifier and ComposeKey are updated to treat the space key as before.

* Enter the best suggestion when the space bar is pressed

* Refactor: Implement backspace as an editing action

* Undo suggestion when delete is pressed

The delete key (backspace internally) undoes the suggestion if the last
action done was entering the suggestion with either the space bar or the
candidates view.

* Add an option to enable space bar autocomplete

This option is off by default. Undoing a completion with backspace works
in any case.

* Refactor: Track selection emptyness in CurrentlyTypedWord

This removes an expensive RPC call.

9 files changed, 190 insertions, 80 deletions

diff --git a/res/values/strings.xml b/res/values/strings.xml
index d46b828..7cc8d1d 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -36,6 +36,8 @@
     <string name="pref_category_suggestions">Suggestions</string>
     <string name="pref_suggestions_title">Suggestions</string>
     <string name="pref_suggestions_summary">Enable word completion and spell checking</string>
+    <string name="pref_space_bar_auto_complete_title">Autocomplete with the space bar</string>
+    <string name="pref_space_bar_auto_complete_summary">Enter the best suggestion by pressing space</string>
     <string name="pref_category_typing">Typing</string>
     <string name="pref_swipe_dist_title">Swiping distance</string>
     <string name="pref_swipe_dist_summary">Distance of characters in the corners of the keys (%s)</string>
diff --git a/res/xml/settings.xml b/res/xml/settings.xml
index a63c9d8..d846dd1 100644
--- a/res/xml/settings.xml
+++ b/res/xml/settings.xml
@@ -14,6 +14,7 @@
   </PreferenceCategory>
   <PreferenceCategory android:title="@string/pref_category_suggestions">
     <CheckBoxPreference android:key="suggestions" android:title="@string/pref_suggestions_title" android:summary="@string/pref_suggestions_summary" android:defaultValue="true"/>
+    <CheckBoxPreference android:key="space_bar_auto_complete" android:title="@string/pref_space_bar_auto_complete_title" android:summary="@string/pref_space_bar_auto_complete_summary" android:defaultValue="false"/>
   </PreferenceCategory>
   <PreferenceCategory android:title="@string/pref_category_typing">
     <ListPreference android:key="swipe_dist" android:title="@string/pref_swipe_dist_title" android:summary="@string/pref_swipe_dist_summary" android:defaultValue="15" android:entries="@array/pref_swipe_dist_entries" android:entryValues="@array/pref_swipe_dist_values"/>
diff --git a/srcs/juloo.keyboard2/ComposeKey.java b/srcs/juloo.keyboard2/ComposeKey.java
index 9571c03..5be9597 100644
--- a/srcs/juloo.keyboard2/ComposeKey.java
+++ b/srcs/juloo.keyboard2/ComposeKey.java
@@ -10,10 +10,14 @@ public final class ComposeKey
   {
     switch (kv.getKind())
     {
-      case Char:
-        return apply(state, kv.getChar());
-      case String:
-        return apply(state, kv.getString());
+      case Char: return apply(state, kv.getChar());
+      case String: return apply(state, kv.getString());
+      case Editing:
+        switch (kv.getEditing())
+        {
+          case SPACE_BAR: return apply(state, ' ');
+        }
+        break;
     }
     return null;
   }
diff --git a/srcs/juloo.keyboard2/Config.java b/srcs/juloo.keyboard2/Config.java
index 2831254..98bb72b 100644
--- a/srcs/juloo.keyboard2/Config.java
+++ b/srcs/juloo.keyboard2/Config.java
@@ -74,6 +74,7 @@ public final class Config
   public int circle_sensitivity;
   public boolean clipboard_history_enabled;
   public int clipboard_history_duration;
+  public boolean space_bar_auto_complete;
 
   // Dynamically set
   /** Configuration options implied by the connected editor. */
@@ -191,6 +192,7 @@ public final class Config
     circle_sensitivity = Integer.valueOf(_prefs.getString("circle_sensitivity", "2"));
     clipboard_history_enabled = _prefs.getBoolean("clipboard_history_enabled", false);
     clipboard_history_duration = Integer.parseInt(_prefs.getString("clipboard_history_duration", "5"));
+    space_bar_auto_complete = _prefs.getBoolean("space_bar_auto_complete", false);
 
     float screen_width_dp = dm.widthPixels / dm.density;
     wide_screen = screen_width_dp >= WIDE_DEVICE_THRESHOLD;
diff --git a/srcs/juloo.keyboard2/CurrentlyTypedWord.java b/srcs/juloo.keyboard2/CurrentlyTypedWord.java
index 8685fb1..40825bb 100644
--- a/srcs/juloo.keyboard2/CurrentlyTypedWord.java
+++ b/srcs/juloo.keyboard2/CurrentlyTypedWord.java
@@ -6,7 +6,8 @@ import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
 import java.util.List;
 
-/** Keep track of the word being typed. */
+/** Keep track of the word being typed. This also tracks whether the selection
+    is empty. */
 public final class CurrentlyTypedWord
 {
   InputConnection _ic = null;
@@ -40,6 +41,11 @@ public final class CurrentlyTypedWord
     return _w.toString();
   }
 
+  public boolean is_selection_not_empty()
+  {
+    return _has_selection;
+  }
+
   public void started(Config conf, InputConnection ic)
   {
     _ic = ic;
diff --git a/srcs/juloo.keyboard2/KeyEventHandler.java b/srcs/juloo.keyboard2/KeyEventHandler.java
index 2bda20c..d078a63 100644
--- a/srcs/juloo.keyboard2/KeyEventHandler.java
+++ b/srcs/juloo.keyboard2/KeyEventHandler.java
@@ -30,6 +30,8 @@ public final class KeyEventHandler
   /** Whether to force sending arrow keys to move the cursor when
       [setSelection] could be used instead. */
   boolean _move_cursor_force_fallback = false;
+  /** Whether the space bar automatically enters the best suggestion. */
+  boolean _space_bar_auto_complete = false;
 
   public KeyEventHandler(IReceiver recv, Config config)
   {
@@ -50,6 +52,8 @@ public final class KeyEventHandler
     _typedword.started(conf, ic);
     _move_cursor_force_fallback =
       conf.editor_config.should_move_cursor_force_fallback;
+    _space_bar_auto_complete = conf.space_bar_auto_complete;
+    clear_space_bar_state();
   }
 
   /** Selection has been updated. */
@@ -123,7 +127,10 @@ public final class KeyEventHandler
   @Override
   public void suggestion_entered(String text)
   {
-    replace_text_before_cursor(_typedword.get().length(), text + " ");
+    String old = _typedword.get();
+    replace_text_before_cursor(old.length(), text + " ");
+    last_replaced_word = old;
+    last_replacement_word_len = text.length() + 1;
   }
 
   @Override
@@ -227,6 +234,7 @@ public final class KeyEventHandler
     {
       _autocap.event_sent(eventCode, metaState);
       _typedword.event_sent(eventCode, metaState);
+      clear_space_bar_state();
     }
   }
 
@@ -238,6 +246,7 @@ public final class KeyEventHandler
     _autocap.typed(text);
     _typedword.typed(text);
     conn.commitText(text, 1);
+    clear_space_bar_state();
   }
 
   void replace_text_before_cursor(int remove_length, String new_text)
@@ -265,9 +274,9 @@ public final class KeyEventHandler
   {
     switch (ev)
     {
-      case COPY: if(is_selection_not_empty()) send_context_menu_action(android.R.id.copy); break;
+      case COPY: if(_typedword.is_selection_not_empty()) send_context_menu_action(android.R.id.copy); break;
       case PASTE: send_context_menu_action(android.R.id.paste); break;
-      case CUT: if(is_selection_not_empty()) send_context_menu_action(android.R.id.cut); break;
+      case CUT: if(_typedword.is_selection_not_empty()) send_context_menu_action(android.R.id.cut); break;
       case SELECT_ALL: send_context_menu_action(android.R.id.selectAll); break;
       case SHARE: send_context_menu_action(android.R.id.shareText); break;
       case PASTE_PLAIN: send_context_menu_action(android.R.id.pasteAsPlainText); break;
@@ -279,6 +288,8 @@ public final class KeyEventHandler
       case DELETE_WORD: send_key_down_up(KeyEvent.KEYCODE_DEL, KeyEvent.META_CTRL_ON | KeyEvent.META_CTRL_LEFT_ON); break;
       case FORWARD_DELETE_WORD: send_key_down_up(KeyEvent.KEYCODE_FORWARD_DEL, KeyEvent.META_CTRL_ON | KeyEvent.META_CTRL_LEFT_ON); break;
       case SELECTION_CANCEL: cancel_selection(); break;
+      case SPACE_BAR: handle_space_bar(); break;
+      case BACKSPACE: handle_backspace(); break;
     }
   }
 
@@ -497,11 +508,43 @@ public final class KeyEventHandler
       _recv.selection_state_changed(false);
   }
 
-  boolean is_selection_not_empty()
+  /** The word that was replaced by a suggestion when the last action was to
+      enter a suggestion (with the space bar or the candidates view) or [null]
+      otherwise. */
+  String last_replaced_word = null;
+  /** Length of the text before the cursor that should be replaced by
+      backspace. */
+  int last_replacement_word_len = 0;
+
+  void handle_space_bar()
   {
-    InputConnection conn = _recv.getCurrentInputConnection();
-    if (conn == null) return false;
-    return (conn.getSelectedText(0) != null);
+    if (_space_bar_auto_complete && _suggestions.best_suggestion != null
+        && !_typedword.is_selection_not_empty())
+    {
+      suggestion_entered(_suggestions.best_suggestion);
+    }
+    else
+    {
+      send_text(" ");
+    }
+  }
+
+  void handle_backspace()
+  {
+    if (last_replaced_word != null)
+    {
+      replace_text_before_cursor(last_replacement_word_len, last_replaced_word);
+      last_replaced_word = null;
+    }
+    else
+    {
+      send_key_down_up(KeyEvent.KEYCODE_DEL);
+    }
+  }
+
+  void clear_space_bar_state()
+  {
+    last_replaced_word = null;
   }
 
   public static interface IReceiver extends Suggestions.Callback
diff --git a/srcs/juloo.keyboard2/KeyModifier.java b/srcs/juloo.keyboard2/KeyModifier.java
index c40c342..3ef16bc 100644
--- a/srcs/juloo.keyboard2/KeyModifier.java
+++ b/srcs/juloo.keyboard2/KeyModifier.java
@@ -178,15 +178,26 @@ public final class KeyModifier
 
   private static KeyValue apply_dead_char(KeyValue k, char dead_char)
   {
+    KeyValue r = null;
     switch (k.getKind())
     {
-      case Char:
-        char c = k.getChar();
-        char modified = (char)KeyCharacterMap.getDeadChar(dead_char, c);
-        if (modified != 0 && modified != c)
-          return KeyValue.makeStringKey(String.valueOf(modified));
+      case Char: r = apply_dead_char(k.getChar(), dead_char); break;
+      case Editing:
+        switch (k.getEditing())
+        {
+          case SPACE_BAR: r = apply_dead_char(' ', dead_char); break;
+        }
+        break;
     }
-    return k;
+    return (r == null) ? k : r;
+  }
+
+  private static KeyValue apply_dead_char(char c, char dead_char)
+  {
+    char modified = (char)KeyCharacterMap.getDeadChar(dead_char, c);
+    if (modified != 0 && modified != c)
+      return KeyValue.makeStringKey(String.valueOf(modified));
+    return null;
   }
 
   private static KeyValue apply_combining_char(KeyValue k, String combining)
@@ -294,6 +305,7 @@ public final class KeyModifier
     {
       case UNDO: return "redo";
       case PASTE: return "pasteAsPlainText";
+      case SPACE_BAR: return "nbsp";
       default: return null;
     }
   }
@@ -313,65 +325,76 @@ public final class KeyModifier
 
   private static KeyValue turn_into_keyevent(KeyValue k)
   {
-    if (k.getKind() != KeyValue.Kind.Char)
-      return k;
     int e;
-    switch (k.getChar())
+    switch (k.getKind())
     {
-      case 'a': e = KeyEvent.KEYCODE_A; break;
-      case 'b': e = KeyEvent.KEYCODE_B; break;
-      case 'c': e = KeyEvent.KEYCODE_C; break;
-      case 'd': e = KeyEvent.KEYCODE_D; break;
-      case 'e': e = KeyEvent.KEYCODE_E; break;
-      case 'f': e = KeyEvent.KEYCODE_F; break;
-      case 'g': e = KeyEvent.KEYCODE_G; break;
-      case 'h': e = KeyEvent.KEYCODE_H; break;
-      case 'i': e = KeyEvent.KEYCODE_I; break;
-      case 'j': e = KeyEvent.KEYCODE_J; break;
-      case 'k': e = KeyEvent.KEYCODE_K; break;
-      case 'l': e = KeyEvent.KEYCODE_L; break;
-      case 'm': e = KeyEvent.KEYCODE_M; break;
-      case 'n': e = KeyEvent.KEYCODE_N; break;
-      case 'o': e = KeyEvent.KEYCODE_O; break;
-      case 'p': e = KeyEvent.KEYCODE_P; break;
-      case 'q': e = KeyEvent.KEYCODE_Q; break;
-      case 'r': e = KeyEvent.KEYCODE_R; break;
-      case 's': e = KeyEvent.KEYCODE_S; break;
-      case 't': e = KeyEvent.KEYCODE_T; break;
-      case 'u': e = KeyEvent.KEYCODE_U; break;
-      case 'v': e = KeyEvent.KEYCODE_V; break;
-      case 'w': e = KeyEvent.KEYCODE_W; break;
-      case 'x': e = KeyEvent.KEYCODE_X; break;
-      case 'y': e = KeyEvent.KEYCODE_Y; break;
-      case 'z': e = KeyEvent.KEYCODE_Z; break;
-      case '0': e = KeyEvent.KEYCODE_0; break;
-      case '1': e = KeyEvent.KEYCODE_1; break;
-      case '2': e = KeyEvent.KEYCODE_2; break;
-      case '3': e = KeyEvent.KEYCODE_3; break;
-      case '4': e = KeyEvent.KEYCODE_4; break;
-      case '5': e = KeyEvent.KEYCODE_5; break;
-      case '6': e = KeyEvent.KEYCODE_6; break;
-      case '7': e = KeyEvent.KEYCODE_7; break;
-      case '8': e = KeyEvent.KEYCODE_8; break;
-      case '9': e = KeyEvent.KEYCODE_9; break;
-      case '`': e = KeyEvent.KEYCODE_GRAVE; break;
-      case '-': e = KeyEvent.KEYCODE_MINUS; break;
-      case '=': e = KeyEvent.KEYCODE_EQUALS; break;
-      case '[': e = KeyEvent.KEYCODE_LEFT_BRACKET; break;
-      case ']': e = KeyEvent.KEYCODE_RIGHT_BRACKET; break;
-      case '\\': e = KeyEvent.KEYCODE_BACKSLASH; break;
-      case ';': e = KeyEvent.KEYCODE_SEMICOLON; break;
-      case '\'': e = KeyEvent.KEYCODE_APOSTROPHE; break;
-      case '/': e = KeyEvent.KEYCODE_SLASH; break;
-      case '@': e = KeyEvent.KEYCODE_AT; break;
-      case '+': e = KeyEvent.KEYCODE_PLUS; break;
-      case ',': e = KeyEvent.KEYCODE_COMMA; break;
-      case '.': e = KeyEvent.KEYCODE_PERIOD; break;
-      case '*': e = KeyEvent.KEYCODE_STAR; break;
-      case '#': e = KeyEvent.KEYCODE_POUND; break;
-      case '(': e = KeyEvent.KEYCODE_NUMPAD_LEFT_PAREN; break;
-      case ')': e = KeyEvent.KEYCODE_NUMPAD_RIGHT_PAREN; break;
-      case ' ': e = KeyEvent.KEYCODE_SPACE; break;
+      case Char:
+        switch (k.getChar())
+        {
+          case 'a': e = KeyEvent.KEYCODE_A; break;
+          case 'b': e = KeyEvent.KEYCODE_B; break;
+          case 'c': e = KeyEvent.KEYCODE_C; break;
+          case 'd': e = KeyEvent.KEYCODE_D; break;
+          case 'e': e = KeyEvent.KEYCODE_E; break;
+          case 'f': e = KeyEvent.KEYCODE_F; break;
+          case 'g': e = KeyEvent.KEYCODE_G; break;
+          case 'h': e = KeyEvent.KEYCODE_H; break;
+          case 'i': e = KeyEvent.KEYCODE_I; break;
+          case 'j': e = KeyEvent.KEYCODE_J; break;
+          case 'k': e = KeyEvent.KEYCODE_K; break;
+          case 'l': e = KeyEvent.KEYCODE_L; break;
+          case 'm': e = KeyEvent.KEYCODE_M; break;
+          case 'n': e = KeyEvent.KEYCODE_N; break;
+          case 'o': e = KeyEvent.KEYCODE_O; break;
+          case 'p': e = KeyEvent.KEYCODE_P; break;
+          case 'q': e = KeyEvent.KEYCODE_Q; break;
+          case 'r': e = KeyEvent.KEYCODE_R; break;
+          case 's': e = KeyEvent.KEYCODE_S; break;
+          case 't': e = KeyEvent.KEYCODE_T; break;
+          case 'u': e = KeyEvent.KEYCODE_U; break;
+          case 'v': e = KeyEvent.KEYCODE_V; break;
+          case 'w': e = KeyEvent.KEYCODE_W; break;
+          case 'x': e = KeyEvent.KEYCODE_X; break;
+          case 'y': e = KeyEvent.KEYCODE_Y; break;
+          case 'z': e = KeyEvent.KEYCODE_Z; break;
+          case '0': e = KeyEvent.KEYCODE_0; break;
+          case '1': e = KeyEvent.KEYCODE_1; break;
+          case '2': e = KeyEvent.KEYCODE_2; break;
+          case '3': e = KeyEvent.KEYCODE_3; break;
+          case '4': e = KeyEvent.KEYCODE_4; break;
+          case '5': e = KeyEvent.KEYCODE_5; break;
+          case '6': e = KeyEvent.KEYCODE_6; break;
+          case '7': e = KeyEvent.KEYCODE_7; break;
+          case '8': e = KeyEvent.KEYCODE_8; break;
+          case '9': e = KeyEvent.KEYCODE_9; break;
+          case '`': e = KeyEvent.KEYCODE_GRAVE; break;
+          case '-': e = KeyEvent.KEYCODE_MINUS; break;
+          case '=': e = KeyEvent.KEYCODE_EQUALS; break;
+          case '[': e = KeyEvent.KEYCODE_LEFT_BRACKET; break;
+          case ']': e = KeyEvent.KEYCODE_RIGHT_BRACKET; break;
+          case '\\': e = KeyEvent.KEYCODE_BACKSLASH; break;
+          case ';': e = KeyEvent.KEYCODE_SEMICOLON; break;
+          case '\'': e = KeyEvent.KEYCODE_APOSTROPHE; break;
+          case '/': e = KeyEvent.KEYCODE_SLASH; break;
+          case '@': e = KeyEvent.KEYCODE_AT; break;
+          case '+': e = KeyEvent.KEYCODE_PLUS; break;
+          case ',': e = KeyEvent.KEYCODE_COMMA; break;
+          case '.': e = KeyEvent.KEYCODE_PERIOD; break;
+          case '*': e = KeyEvent.KEYCODE_STAR; break;
+          case '#': e = KeyEvent.KEYCODE_POUND; break;
+          case '(': e = KeyEvent.KEYCODE_NUMPAD_LEFT_PAREN; break;
+          case ')': e = KeyEvent.KEYCODE_NUMPAD_RIGHT_PAREN; break;
+          case ' ': e = KeyEvent.KEYCODE_SPACE; break;
+          default: return k;
+        }
+        break;
+      case Editing:
+        switch (k.getEditing())
+        {
+          case SPACE_BAR: e = KeyEvent.KEYCODE_SPACE; break;
+          default: return k;
+        }
+        break;
       default: return k;
     }
     return k.withKeyevent(e);
@@ -409,6 +432,12 @@ public final class KeyModifier
           case KeyEvent.KEYCODE_FORWARD_DEL: name = "forward_delete_word"; break;
         }
         break;
+      case Editing:
+        switch (k.getEditing())
+        {
+          case BACKSPACE: name = "delete_word"; break;
+        }
+        break;
     }
     return (name == null) ? k : KeyValue.getKeyByName(name);
   }
@@ -437,6 +466,12 @@ public final class KeyModifier
           case KeyEvent.KEYCODE_ESCAPE: name = "selection_cancel"; break;
         }
         break;
+      case Editing:
+        switch (k.getEditing())
+        {
+          case SPACE_BAR: name = "selection_cancel"; break;
+        }
+        break;
     }
     return (name == null) ? k : KeyValue.getKeyByName(name);
   }
diff --git a/srcs/juloo.keyboard2/KeyValue.java b/srcs/juloo.keyboard2/KeyValue.java
index 1fb84f4..769bd29 100644
--- a/srcs/juloo.keyboard2/KeyValue.java
+++ b/srcs/juloo.keyboard2/KeyValue.java
@@ -81,6 +81,8 @@ public final class KeyValue implements Comparable<KeyValue>
     DELETE_WORD,
     FORWARD_DELETE_WORD,
     SELECTION_CANCEL,
+    SPACE_BAR,
+    BACKSPACE,
   }
 
   public static enum Placeholder
@@ -401,7 +403,12 @@ public final class KeyValue implements Comparable<KeyValue>
 
   private static KeyValue editingKey(int symbol, Editing action)
   {
-    return editingKey(String.valueOf((char)symbol), action, FLAG_KEY_FONT);
+    return editingKey(symbol, action, 0);
+  }
+
+  private static KeyValue editingKey(int symbol, Editing action, int flags)
+  {
+    return editingKey(String.valueOf((char)symbol), action, flags | FLAG_KEY_FONT);
   }
 
   /** A key that slides the property specified by [s] by the amount specified
@@ -658,7 +665,6 @@ public final class KeyValue implements Comparable<KeyValue>
       case "page_down": return keyeventKey(0xE003, KeyEvent.KEYCODE_PAGE_DOWN, 0);
       case "home": return keyeventKey(0xE00B, KeyEvent.KEYCODE_MOVE_HOME, FLAG_SMALLER_FONT);
       case "end": return keyeventKey(0xE00C, KeyEvent.KEYCODE_MOVE_END, FLAG_SMALLER_FONT);
-      case "backspace": return keyeventKey(0xE011, KeyEvent.KEYCODE_DEL, 0);
       case "delete": return keyeventKey(0xE010, KeyEvent.KEYCODE_FORWARD_DEL, 0);
       case "insert": return keyeventKey("Ins", KeyEvent.KEYCODE_INSERT, FLAG_SMALLER_FONT);
       case "f1": return keyeventKey("F1", KeyEvent.KEYCODE_F1, 0);
@@ -680,7 +686,7 @@ public final class KeyValue implements Comparable<KeyValue>
       /* Spaces */
       case "\\t": return charKey("\\t", '\t', 0); // Send the tab character
       case "\\n": return charKey("\\n", '\n', 0); // Send the newline character
-      case "space": return charKey(0xE00D, ' ', FLAG_SMALLER_FONT | FLAG_GREYED);
+      case "space": return editingKey(0xE00D, Editing.SPACE_BAR, FLAG_SMALLER_FONT | FLAG_GREYED);
       case "nbsp": return charKey("\u237d", '\u00a0', FLAG_SMALLER_FONT);
       case "nnbsp": return charKey("\u2423", '\u202F', FLAG_SMALLER_FONT);
 
@@ -729,6 +735,7 @@ public final class KeyValue implements Comparable<KeyValue>
       case "halfspace": return charKey(0xE018, '\u200C', 0); // zero-width non joiner
 
       /* Editing keys */
+      case "backspace": return editingKey(0xE011, Editing.BACKSPACE, 0);
       case "copy": return editingKey(0xE030, Editing.COPY);
       case "paste": return editingKey(0xE032, Editing.PASTE);
       case "cut": return editingKey(0xE031, Editing.CUT);
diff --git a/srcs/juloo.keyboard2/suggestions/Suggestions.java b/srcs/juloo.keyboard2/suggestions/Suggestions.java
index 998d40d..89ed86e 100644
--- a/srcs/juloo.keyboard2/suggestions/Suggestions.java
+++ b/srcs/juloo.keyboard2/suggestions/Suggestions.java
@@ -13,6 +13,10 @@ public final class Suggestions
   Callback _callback;
   Config _config;
 
+  /** The suggestion displayed at the center of the candidates view and entered
+      by the space bar. */
+  public String best_suggestion = null;
+
   public Suggestions(Callback c, Config conf)
   {
     _callback = c;
@@ -24,7 +28,7 @@ public final class Suggestions
     Cdict dict = _config.current_dictionary;
     if (word.length() < 2 || dict == null)
     {
-      _callback.set_suggestions(NO_SUGGESTIONS);
+      set_suggestions(NO_SUGGESTIONS);
     }
     else
     {
@@ -42,10 +46,16 @@ public final class Suggestions
         if (dist.length > j && i < 3)
           suggestions[i++] = dict.word(dist[j]);
       }
-      _callback.set_suggestions(Arrays.asList(suggestions));
+      set_suggestions(Arrays.asList(suggestions));
     }
   }
 
+  void set_suggestions(List<String> ws)
+  {
+    _callback.set_suggestions(ws);
+    best_suggestion = (ws.size() > 0) ? ws.get(0) : null;
+  }
+
   static final List<String> NO_SUGGESTIONS = Arrays.asList();
 
   public static interface Callback