diff --git a/Source/InputMethodController.h b/Source/InputMethodController.h
index a68caccc..fb3b8e38 100644
--- a/Source/InputMethodController.h
+++ b/Source/InputMethodController.h
@@ -61,6 +61,9 @@
     
     // currently available candidates
     NSMutableArray *_candidates;
+
+    // current input mode
+    NSString *_inputMode;
 }
 @end
 
diff --git a/Source/InputMethodController.mm b/Source/InputMethodController.mm
index 37e8da84..95fb4bf6 100644
--- a/Source/InputMethodController.mm
+++ b/Source/InputMethodController.mm
@@ -79,6 +79,10 @@ static NSString *const kCandidateTextFontName = @"CandidateTextFontName";
 static NSString *const kCandidateKeyLabelFontName = @"CandidateKeyLabelFontName";
 static NSString *const kCandidateKeys = @"CandidateKeys";
 
+// input modes
+static NSString *const kBopomofoModeIdentifier = @"org.openvanilla.inputmethod.McBopomofo.Bopomofo";
+static NSString *const kPlainBopomofoModeIdentifier = @"org.openvanilla.inputmethod.McBopomofo.PlainBopomofo";
+
 // key code enums
 enum {
     kUpKeyCode = 126,
@@ -179,6 +183,8 @@ public:
         if (![[NSUserDefaults standardUserDefaults] objectForKey:kDisableUserCandidateSelectionLearning]) {
             [[NSUserDefaults standardUserDefaults] setObject:(id)kCFBooleanTrue forKey:kDisableUserCandidateSelectionLearning];
         }
+
+        _inputMode = kBopomofoModeIdentifier;
     }
 
     return self;
@@ -262,9 +268,6 @@ public:
             _bpmfReadingBuffer->setKeyboardLayout(BopomofoKeyboardLayout::StandardLayout());
             [[NSUserDefaults standardUserDefaults] setInteger:0 forKey:kKeyboardLayoutPreferenceKey];
     }
-    if (keyboardLayout < 4) {
-        [client overrideKeyboardWithKeyboardNamed:@"com.apple.keylayout.US"];
-    }
 
     // set the size
     NSInteger textSize = [[NSUserDefaults standardUserDefaults] integerForKey:kCandidateListTextSizeKey];
@@ -301,6 +304,27 @@ public:
     [_candidates removeAllObjects];
 }
 
+- (void)setValue:(id)value forTag:(long)tag client:(id)sender
+{
+    if ([value isKindOfClass:[NSString class]] && [value isEqual:kPlainBopomofoModeIdentifier]) {
+        _inputMode = kPlainBopomofoModeIdentifier;
+    }
+    else {
+        _inputMode = kBopomofoModeIdentifier;
+    }
+
+    [sender overrideKeyboardWithKeyboardNamed:@"com.apple.keylayout.US"];
+
+    if (!_bpmfReadingBuffer->isEmpty()) {
+        _bpmfReadingBuffer->clear();
+        [self updateClientComposingBuffer:sender];
+    }
+
+    if ([_composingBuffer length] > 0) {
+        [self commitComposition:sender];
+    }
+}
+
 #pragma mark - IMKServerInput protocol methods
 
 - (void)commitComposition:(id)client
@@ -462,9 +486,25 @@ public:
 
 - (BOOL)handleCandidateEventWithInputText:(NSString *)inputText charCode:(UniChar)charCode keyCode:(NSUInteger)keyCode
 {
+    if (_inputMode == kPlainBopomofoModeIdentifier) {
+        if (charCode == '<') {
+            keyCode = kPageUpKeyCode;
+        }
+        else if (charCode == '>') {
+            keyCode = kPageDownKeyCode;
+        }
+    }
+
     if (charCode == 27) {
         gCurrentCandidateController.visible = NO;
         [_candidates removeAllObjects];
+
+        if (_inputMode == kPlainBopomofoModeIdentifier) {
+            _builder->clear();
+            _walkedNodes.clear();
+            [_composingBuffer setString:@""];
+        }
+        [self updateClientComposingBuffer:_currentCandidateClient];
         return YES;
     }
     else if (charCode == 13 || keyCode == 127) {
@@ -564,8 +604,7 @@ public:
         
         return YES;            
     }
-    else {
-        
+    else {        
         NSInteger index = NSNotFound;
         for (NSUInteger j = 0, c = [gCurrentCandidateController.keyLabels count]; j < c; j++) {
             if ([inputText compare:[gCurrentCandidateController.keyLabels objectAtIndex:j] options:NSCaseInsensitiveSearch] == NSOrderedSame) {
@@ -582,6 +621,16 @@ public:
                 return YES;
             }
         }
+
+        if (_inputMode == kPlainBopomofoModeIdentifier) {
+            if (_bpmfReadingBuffer->isValidKey((char)charCode)) {
+                NSUInteger candidateIndex = [gCurrentCandidateController candidateIndexAtKeyLabelIndex:0];
+                if (candidateIndex != NSUIntegerMax) {
+                    [self candidateController:gCurrentCandidateController didSelectCandidateAtIndex:candidateIndex];
+                    return [self inputText:inputText key:keyCode modifiers:0 client:_currentCandidateClient];
+                }
+            }
+        }
         
         [self beep];            
         return YES;
@@ -716,6 +765,10 @@ public:
         _bpmfReadingBuffer->clear();
         [self updateClientComposingBuffer:client];
 
+        if (_inputMode == kPlainBopomofoModeIdentifier) {
+            [self _showCandidateWindowUsingVerticalMode:useVerticalMode client:client];
+        }
+
         // and tells the client that the key is consumed
         return YES;
     }
@@ -895,6 +948,11 @@ public:
             [self beep];
         }
         [self updateClientComposingBuffer:client];
+
+        if (_inputMode == kPlainBopomofoModeIdentifier) {
+            [self _showCandidateWindowUsingVerticalMode:useVerticalMode client:client];
+        }
+
         return YES;
     }
 
@@ -909,6 +967,17 @@ public:
             [self beep];
         }
         [self updateClientComposingBuffer:client];
+
+        if (_inputMode == kPlainBopomofoModeIdentifier) {
+            [self collectCandidates];
+            if ([_candidates count] == 1) {
+                [self commitComposition:client];
+            }
+            else {
+                [self _showCandidateWindowUsingVerticalMode:useVerticalMode client:client];
+            }
+        }
+
         return YES;
     }
 
@@ -1104,6 +1173,11 @@ public:
     
     gCurrentCandidateController.keyLabels = keyLabels;
     [self collectCandidates];
+
+    if (_inputMode == kPlainBopomofoModeIdentifier && [_candidates count] == 1) {
+        [self commitComposition:client];
+        return;
+    }
     
     gCurrentCandidateController.delegate = self;
     [gCurrentCandidateController reloadData];
@@ -1213,6 +1287,11 @@ public:
     
     [self walk];
     [self updateClientComposingBuffer:_currentCandidateClient];
+
+    if (_inputMode == kPlainBopomofoModeIdentifier) {
+        [self commitComposition:_currentCandidateClient];
+        return;
+    }
 }
 
 @end