diff --git a/scim-wnn/src/romkan.cpp b/scim-wnn/src/romkan.cpp
index 29bf546..e2aaa69 100644
--- a/scim-wnn/src/romkan.cpp
+++ b/scim-wnn/src/romkan.cpp
@@ -77,6 +77,7 @@
  */
 WideString Romkan::insert(char k)
 {
+    if (k == 0) return(text);
     buf += k;
     String s;
     s = k;
diff --git a/scim-wnn/src/scim_wnn_imengine.cpp b/scim-wnn/src/scim_wnn_imengine.cpp
index 326b830..88da807 100644
--- a/scim-wnn/src/scim_wnn_imengine.cpp
+++ b/scim-wnn/src/scim_wnn_imengine.cpp
@@ -248,6 +248,8 @@
 {
 }
 
+
+
 bool WnnInstance::process_key_event (const KeyEvent& key)
 {
     if (key.is_key_release()) return false;
@@ -267,93 +269,73 @@
         update_preedit_caret(m_rk.getPos());
         return(true);
     } else
-    if (k_conversion_start.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
+    if (m_rk.getTextLength()) {
+        if (k_conversion_start.comp(key)) {
+            startConversion(m_rk.getText(true));
+            alp_count ++;
+            show_preedit_string();
+            if (m_conversion) {
+                update_preedit_string(wnn.getText(),wnn.getAttributeList());
+                update_preedit_caret(wnn.getCaretPos());
+                if (alp == -1) {
+                    if (!m_lookup) startLookup();
+                }
+            }
+            return(true);
+        } else
+        if (k_commit.comp(key)) {
+            commit_string(m_rk.getText(true));
+            m_rk.reset();
+            hide_preedit_string();
+            return(true);
+        } else
+        if (k_forward.comp(key) || k_backward.comp(key)) {
+            k_backward.comp(key) ? m_rk.setPos(m_rk.getPos() - 1) : m_rk.setPos(m_rk.getPos() + 1);
+            update_preedit_string(m_rk.getText());
+            update_preedit_caret(m_rk.getPos());
+            return(true);
+        } else
+        if (k_backspace.comp(key)) {
+            m_rk.backspace();
+            update_preedit_string(m_rk.getText());
+            update_preedit_caret(m_rk.getPos());
+            return(true);
+        } else
+        if (k_delete.comp(key)) {
+            m_rk.del();
+            update_preedit_string(m_rk.getText());
+            update_preedit_caret(m_rk.getPos());
+            return(true);
+        } else
+        if (k_cancel.comp(key)) {
+            m_rk.reset();
+            hide_preedit_string();
+            return(true);
+        } else
+        if (k_convert_hiragana.comp(key)) {
+            m_rk.kataHira();
+            update_preedit_string(m_rk.getText());
+            update_preedit_caret(m_rk.getPos());
+            return(true);
+        } else
+        if (k_convert_katakana.comp(key)) {
+            m_rk.hiraKata();
+            update_preedit_string(m_rk.getText());
+            update_preedit_caret(m_rk.getPos());
+            return(true);
         }
-        startConversion(m_rk.getText(true));
-        alp_count ++;
-        show_preedit_string();
-        if (m_conversion) {
-            update_preedit_string(wnn.getText(),wnn.getAttributeList());
-            update_preedit_caret(wnn.getCaretPos());
-        }
-        if (alp == -1) {
-            if (!m_lookup) startLookup();
-        }
-        return(true);
-    } else
-    if (k_commit.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        commit_string(m_rk.getText(true));
-        m_rk.reset();
-        hide_preedit_string();
-        return(true);
-    } else
-    if (k_forward.comp(key) || k_backward.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        k_backward.comp(key) ? m_rk.setPos(m_rk.getPos() - 1) : m_rk.setPos(m_rk.getPos() + 1);
-        update_preedit_string(m_rk.getText());
-        update_preedit_caret(m_rk.getPos());
-        return(true);
-    } else
-    if (k_backspace.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        m_rk.backspace();
-        update_preedit_string(m_rk.getText());
-        update_preedit_caret(m_rk.getPos());
-        return(true);
-    } else
-    if (k_delete.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        m_rk.del();
-        update_preedit_string(m_rk.getText());
-        update_preedit_caret(m_rk.getPos());
-        return(true);
-    } else
-    if (k_cancel.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        m_rk.reset();
-        hide_preedit_string();
-        return(true);
-    } else
-    if (k_convert_hiragana.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        m_rk.kataHira();
-        update_preedit_string(m_rk.getText());
-        update_preedit_caret(m_rk.getPos());
-        return(true);
-    } else
-    if (k_convert_katakana.comp(key)) {
-        if (!m_rk.getTextLength()) {
-            return(false);
-        }
-        m_rk.hiraKata();
-        update_preedit_string(m_rk.getText());
-        update_preedit_caret(m_rk.getPos());
-        return(true);
-    } else
+    }
     if (isprint(key.code)) {
         if (key.mask & (SCIM_KEY_AltMask | SCIM_KEY_ControlMask)) return(false);
+        // �Хåե������λ��ι�Ƭ���ڡ�����ľ�����ϡ�
+        if ((key.code == SCIM_KEY_space) && (!m_rk.getTextLength())) return(false);
         show_preedit_string();
         SCIM_DEBUG_IMENGINE(1) << key.get_key_string() << "\n";
         update_preedit_string(m_rk.insert(key.get_ascii_code()));
         update_preedit_caret(m_rk.getPos());
-        return true;
+        return(true);
     }
-    return false;
+    return(false);
 }
 
 /*!
@@ -667,3 +649,5 @@
     show_aux_string();
     show_lookup_table();
 }
+
+