diff --git a/src/plugins/debugger/qml/qmldebuggerclient.h b/src/plugins/debugger/qml/qmldebuggerclient.h
index a1ceeafac52..984869cf098 100644
--- a/src/plugins/debugger/qml/qmldebuggerclient.h
+++ b/src/plugins/debugger/qml/qmldebuggerclient.h
@@ -62,9 +62,10 @@ public:
 
     virtual void activateFrame(int index) = 0;
 
-    virtual void insertBreakpoints(BreakHandler *handler, BreakpointModelId *id) = 0;
-    virtual void removeBreakpoints(BreakpointModelId *id) = 0;
-    virtual void setBreakpoints() = 0;
+    virtual void insertBreakpoint(BreakpointModelId id, BreakHandler *handler) = 0;
+    virtual void removeBreakpoint(BreakpointModelId id, BreakHandler *handler) = 0;
+    virtual void changeBreakpoint(BreakpointModelId id, BreakHandler *handler) = 0;
+    virtual void updateBreakpoints() = 0;
 
     virtual void assignValueInDebugger(const QByteArray expr, const quint64 &id,
                                        const QString &property, const QString value) = 0;
@@ -75,7 +76,6 @@ public:
     virtual void synchronizeWatchers(const QStringList &watchers) = 0;
 
     virtual void expandObject(const QByteArray &iname, quint64 objectId) = 0;
-    virtual void sendPing() = 0;
 
     virtual void setEngine(QmlEngine *engine) = 0;
 
diff --git a/src/plugins/debugger/qml/qmlengine.cpp b/src/plugins/debugger/qml/qmlengine.cpp
index 06a880e3655..06f4d53d1c4 100644
--- a/src/plugins/debugger/qml/qmlengine.cpp
+++ b/src/plugins/debugger/qml/qmlengine.cpp
@@ -491,8 +491,73 @@ void QmlEngine::selectThread(int index)
     Q_UNUSED(index)
 }
 
+void QmlEngine::insertBreakpoint(BreakpointModelId id)
+{
+    BreakHandler *handler = breakHandler();
+    BreakpointState state = handler->state(id);
+    QTC_ASSERT(state == BreakpointInsertRequested, qDebug() << id << this << state);
+    handler->notifyBreakpointInsertProceeding(id);
+
+    if (d->m_adapter.activeDebuggerClient()) {
+        d->m_adapter.activeDebuggerClient()->insertBreakpoint(id,handler);
+    } else {
+        foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients()) {
+            client->insertBreakpoint(id,handler);
+        }
+    }
+
+    if (handler->state(id) == BreakpointInsertProceeding) {
+        handler->notifyBreakpointInsertOk(id);
+    }
+}
+
+void QmlEngine::removeBreakpoint(BreakpointModelId id)
+{
+    BreakHandler *handler = breakHandler();
+    BreakpointState state = handler->state(id);
+    QTC_ASSERT(state == BreakpointRemoveRequested, qDebug() << id << this << state);
+    handler->notifyBreakpointRemoveProceeding(id);
+
+    if (d->m_adapter.activeDebuggerClient()) {
+        d->m_adapter.activeDebuggerClient()->removeBreakpoint(id,handler);
+    } else {
+        foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients()) {
+            client->removeBreakpoint(id,handler);
+        }
+    }
+
+    if (handler->state(id) == BreakpointRemoveProceeding) {
+        handler->notifyBreakpointRemoveOk(id);
+    }
+}
+
+void QmlEngine::changeBreakpoint(BreakpointModelId id)
+{
+    BreakHandler *handler = breakHandler();
+    BreakpointState state = handler->state(id);
+    QTC_ASSERT(state == BreakpointChangeRequested, qDebug() << id << this << state);
+    handler->notifyBreakpointChangeProceeding(id);
+
+    if (d->m_adapter.activeDebuggerClient()) {
+        d->m_adapter.activeDebuggerClient()->changeBreakpoint(id,handler);
+    } else {
+        foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients()) {
+            client->changeBreakpoint(id,handler);
+        }
+    }
+
+    if (handler->state(id) == BreakpointChangeProceeding) {
+        handler->notifyBreakpointChangeOk(id);
+    }
+}
+
 void QmlEngine::attemptBreakpointSynchronization()
 {
+    if (!stateAcceptsBreakpointChanges()) {
+        showMessage(_("BREAKPOINT SYNCHRONIZATION NOT POSSIBLE IN CURRENT STATE"));
+        return;
+    }
+
     BreakHandler *handler = breakHandler();
 
     foreach (BreakpointModelId id, handler->unclaimedBreakpointIds()) {
@@ -501,45 +566,39 @@ void QmlEngine::attemptBreakpointSynchronization()
             handler->setEngine(id, this);
     }
 
-    QStringList breakPointsStr;
     foreach (BreakpointModelId id, handler->engineBreakpointIds(this)) {
-        if (handler->state(id) == BreakpointRemoveRequested) {
-            handler->notifyBreakpointRemoveProceeding(id);
-            if (d->m_adapter.activeDebuggerClient())
-                d->m_adapter.activeDebuggerClient()->removeBreakpoints(&id);
-            else {
-                foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients()) {
-                    client->removeBreakpoints(&id);
-                }
-            }
-            handler->notifyBreakpointRemoveOk(id);
-        } else {
-            if (handler->state(id) == BreakpointInsertRequested) {
-                handler->notifyBreakpointInsertProceeding(id);
-            }
-            if (d->m_adapter.activeDebuggerClient())
-                d->m_adapter.activeDebuggerClient()->insertBreakpoints(handler,&id);
-            else {
-                foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients()) {
-                    client->insertBreakpoints(handler,&id);
-                }
-            }
-            if (handler->state(id) == BreakpointInsertProceeding) {
-                handler->notifyBreakpointInsertOk(id);
-            }
-            breakPointsStr << QString("('%1' '%2' %3)").arg(QString(handler->functionName(id).toUtf8()),
-                                      QString(QUrl::fromLocalFile(handler->fileName(id)).toString().toUtf8()), QString::number(handler->lineNumber(id)));
+        switch (handler->state(id)) {
+        case BreakpointNew:
+            // Should not happen once claimed.
+            QTC_CHECK(false);
+            continue;
+        case BreakpointInsertRequested:
+            insertBreakpoint(id);
+            continue;
+        case BreakpointChangeRequested:
+            changeBreakpoint(id);
+            continue;
+        case BreakpointRemoveRequested:
+            removeBreakpoint(id);
+            continue;
+        case BreakpointChangeProceeding:
+        case BreakpointInsertProceeding:
+        case BreakpointRemoveProceeding:
+        case BreakpointInserted:
+        case BreakpointDead:
+            continue;
         }
+        QTC_ASSERT(false, qDebug() << "UNKNOWN STATE"  << id << state());
     }
 
-    logMessage(LogSend, QString("%1 [%2]").arg(QString("BREAKPOINTS"), breakPointsStr.join(", ")));
+    DebuggerEngine::attemptBreakpointSynchronization();
 
     if (d->m_adapter.activeDebuggerClient()) {
-        d->m_adapter.activeDebuggerClient()->setBreakpoints();
-    }
-    else {
-        foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients())
-            client->setBreakpoints();
+        d->m_adapter.activeDebuggerClient()->updateBreakpoints();
+    } else {
+        foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients()) {
+            client->updateBreakpoints();
+        }
     }
 }
 
@@ -631,8 +690,7 @@ void QmlEngine::synchronizeWatchers()
                    QString("WATCH_EXPRESSIONS"), watchedExpressions.join(", ")));
     if (d->m_adapter.activeDebuggerClient()) {
         d->m_adapter.activeDebuggerClient()->synchronizeWatchers(watchedExpressions);
-    }
-    else {
+    } else {
         foreach (QmlDebuggerClient *client, d->m_adapter.debuggerClients())
             client->synchronizeWatchers(watchedExpressions);
     }
diff --git a/src/plugins/debugger/qml/qmlengine.h b/src/plugins/debugger/qml/qmlengine.h
index ae96ad1d261..25b9996b45d 100644
--- a/src/plugins/debugger/qml/qmlengine.h
+++ b/src/plugins/debugger/qml/qmlengine.h
@@ -107,6 +107,9 @@ private:
     void selectThread(int index);
 
     void attemptBreakpointSynchronization();
+    void insertBreakpoint(BreakpointModelId id);
+    void removeBreakpoint(BreakpointModelId id);
+    void changeBreakpoint(BreakpointModelId id);
     bool acceptsBreakpoint(BreakpointModelId id) const;
 
     void assignValueInDebugger(const WatchData *data,
diff --git a/src/plugins/debugger/qml/qmlv8debuggerclient.cpp b/src/plugins/debugger/qml/qmlv8debuggerclient.cpp
index b31840cc1a2..0e1d9a41234 100644
--- a/src/plugins/debugger/qml/qmlv8debuggerclient.cpp
+++ b/src/plugins/debugger/qml/qmlv8debuggerclient.cpp
@@ -197,33 +197,32 @@ void QmlV8DebuggerClient::activateFrame(int index)
     setLocals(index);
 }
 
-void QmlV8DebuggerClient::insertBreakpoints(BreakHandler *handler, BreakpointModelId *id)
+void QmlV8DebuggerClient::insertBreakpoint(BreakpointModelId id, BreakHandler *handler)
 {
     QByteArray request;
 
     JsonInputStream(request) << '{' << INITIALPARAMS ;
     JsonInputStream(request) << ',' << "command" << ':' << "setbreakpoint";
     JsonInputStream(request) << ',' << "arguments" << ':' << '{';
-    if (handler->breakpointData(*id).type == BreakpointByFileAndLine) {
+    if (handler->breakpointData(id).type == BreakpointByFileAndLine) {
         JsonInputStream(request) << "type" << ':' << "script";
-        JsonInputStream(request) << ',' << "target" << ':' << QFileInfo(handler->fileName(*id)).fileName().toUtf8();
-        JsonInputStream(request) << ',' << "line" << ':' << handler->lineNumber(*id) - 1;
-    } else if (handler->breakpointData(*id).type == BreakpointByFunction) {
+        JsonInputStream(request) << ',' << "target" << ':' << QFileInfo(handler->fileName(id)).fileName().toUtf8();
+        JsonInputStream(request) << ',' << "line" << ':' << handler->lineNumber(id) - 1;
+    } else if (handler->breakpointData(id).type == BreakpointByFunction) {
         JsonInputStream(request) << "type" << ':' << "function";
-        JsonInputStream(request) << ',' << "target" << ':' << handler->functionName(*id).toUtf8();
+        JsonInputStream(request) << ',' << "target" << ':' << handler->functionName(id).toUtf8();
     }
     JsonInputStream(request) << '}';
     JsonInputStream(request) << '}';
 
-    d->breakpointsSync.insert(d->sequence,*id);
+    d->breakpointsSync.insert(d->sequence,id);
     sendMessage(packMessage(request));
-
 }
 
-void QmlV8DebuggerClient::removeBreakpoints(BreakpointModelId *id)
+void QmlV8DebuggerClient::removeBreakpoint(BreakpointModelId id, BreakHandler * /*handler*/)
 {
-    QList<int> breakpoints = d->breakpoints.values(*id);
-    d->breakpoints.remove(*id);
+    QList<int> breakpoints = d->breakpoints.values(id);
+    d->breakpoints.remove(id);
 
     foreach (int bp, breakpoints) {
         QByteArray request;
@@ -241,7 +240,11 @@ void QmlV8DebuggerClient::removeBreakpoints(BreakpointModelId *id)
     }
 }
 
-void QmlV8DebuggerClient::setBreakpoints()
+void QmlV8DebuggerClient::changeBreakpoint(BreakpointModelId /*id*/, BreakHandler * /*handler*/)
+{
+}
+
+void QmlV8DebuggerClient::updateBreakpoints()
 {
 }
 
@@ -318,17 +321,6 @@ void QmlV8DebuggerClient::expandObject(const QByteArray &iname, quint64 objectId
 
 }
 
-void QmlV8DebuggerClient::sendPing()
-{
-    QByteArray request;
-
-    JsonInputStream(request) << '{' << INITIALPARAMS ;
-    JsonInputStream(request) << ',' << "command" << ':' << "ping" << '}';
-
-    d->ping = d->sequence;
-    sendMessage(packMessage(request));
-}
-
 void QmlV8DebuggerClient::backtrace()
 {
     QByteArray request;
@@ -362,9 +354,7 @@ void QmlV8DebuggerClient::messageReceived(const QByteArray &data)
             }
 
             QString debugCommand(value.findChild("command").toVariant().toString());
-            if (debugCommand == "pong") {
-                //DO NOTHING
-            } else if (debugCommand == "backtrace") {
+            if (debugCommand == "backtrace") {
                 setStackFrames(response);
 
             } else if (debugCommand == "lookup") {
diff --git a/src/plugins/debugger/qml/qmlv8debuggerclient.h b/src/plugins/debugger/qml/qmlv8debuggerclient.h
index 870f07b78d9..f446bb65b0b 100644
--- a/src/plugins/debugger/qml/qmlv8debuggerclient.h
+++ b/src/plugins/debugger/qml/qmlv8debuggerclient.h
@@ -62,9 +62,10 @@ public:
 
     void activateFrame(int index);
 
-    void insertBreakpoints(BreakHandler *handler, BreakpointModelId *id);
-    void removeBreakpoints(BreakpointModelId *id);
-    void setBreakpoints();
+    void insertBreakpoint(BreakpointModelId id, BreakHandler *handler);
+    void removeBreakpoint(BreakpointModelId id, BreakHandler *handler);
+    void changeBreakpoint(BreakpointModelId id, BreakHandler *handler);
+    void updateBreakpoints();
 
     void assignValueInDebugger(const QByteArray expr, const quint64 &id,
                                        const QString &property, const QString value);
@@ -75,7 +76,6 @@ public:
     void synchronizeWatchers(const QStringList &watchers);
 
     void expandObject(const QByteArray &iname, quint64 objectId);
-    void sendPing();
 
     void setEngine(QmlEngine *engine);
 
diff --git a/src/plugins/debugger/qml/qscriptdebuggerclient.cpp b/src/plugins/debugger/qml/qscriptdebuggerclient.cpp
index 1318c81e106..bbeed2c99c6 100644
--- a/src/plugins/debugger/qml/qscriptdebuggerclient.cpp
+++ b/src/plugins/debugger/qml/qscriptdebuggerclient.cpp
@@ -202,21 +202,29 @@ void QScriptDebuggerClient::activateFrame(int index)
     sendMessage(reply);
 }
 
-void QScriptDebuggerClient::insertBreakpoints(BreakHandler *handler, BreakpointModelId *id)
+void QScriptDebuggerClient::insertBreakpoint(BreakpointModelId id, BreakHandler *handler)
 {
     JSAgentBreakpointData bp;
-    bp.fileUrl = QUrl::fromLocalFile(handler->fileName(*id)).toString().toUtf8();
-    bp.lineNumber = handler->lineNumber(*id);
-    bp.functionName = handler->functionName(*id).toUtf8();
+    bp.fileUrl = QUrl::fromLocalFile(handler->fileName(id)).toString().toUtf8();
+    bp.lineNumber = handler->lineNumber(id);
+    bp.functionName = handler->functionName(id).toUtf8();
     d->breakpoints.insert(bp);
 }
 
-void QScriptDebuggerClient::removeBreakpoints(BreakpointModelId * /*id*/)
+void QScriptDebuggerClient::removeBreakpoint(BreakpointModelId id, BreakHandler *handler)
 {
-
+    JSAgentBreakpointData bp;
+    bp.fileUrl = QUrl::fromLocalFile(handler->fileName(id)).toString().toUtf8();
+    bp.lineNumber = handler->lineNumber(id);
+    bp.functionName = handler->functionName(id).toUtf8();
+    d->breakpoints.remove(bp);
 }
 
-void QScriptDebuggerClient::setBreakpoints()
+void QScriptDebuggerClient::changeBreakpoint(BreakpointModelId /*id*/, BreakHandler * /*handler*/)
+{
+}
+
+void QScriptDebuggerClient::updateBreakpoints()
 {
     QByteArray reply;
     QDataStream rs(&reply, QIODevice::WriteOnly);
@@ -224,8 +232,6 @@ void QScriptDebuggerClient::setBreakpoints()
     rs << cmd
        << d->breakpoints;
     sendMessage(reply);
-
-    d->breakpoints.clear();
 }
 
 void QScriptDebuggerClient::assignValueInDebugger(const QByteArray expr, const quint64 &id,
diff --git a/src/plugins/debugger/qml/qscriptdebuggerclient.h b/src/plugins/debugger/qml/qscriptdebuggerclient.h
index d8b69353503..9cc5c40cef1 100644
--- a/src/plugins/debugger/qml/qscriptdebuggerclient.h
+++ b/src/plugins/debugger/qml/qscriptdebuggerclient.h
@@ -61,9 +61,10 @@ public:
 
     void activateFrame(int index);
 
-    void insertBreakpoints(BreakHandler *handler, BreakpointModelId *id);
-    void removeBreakpoints(BreakpointModelId *id);
-    void setBreakpoints();
+    void insertBreakpoint(BreakpointModelId id, BreakHandler *handler);
+    void removeBreakpoint(BreakpointModelId id, BreakHandler *handler);
+    void changeBreakpoint(BreakpointModelId id, BreakHandler *handler);
+    void updateBreakpoints();
 
     void assignValueInDebugger(const QByteArray expr, const quint64 &id,
                                        const QString &property, const QString value);
@@ -74,7 +75,6 @@ public:
     void synchronizeWatchers(const QStringList &watchers);
 
     void expandObject(const QByteArray &iname, quint64 objectId);
-    void sendPing();
 
     void setEngine(QmlEngine *engine);
 
@@ -84,6 +84,9 @@ signals:
 protected:
     void messageReceived(const QByteArray &data);
 
+private:
+    void sendPing();
+
 private:
     QScriptDebuggerClientPrivate *d;
     friend class QScriptDebuggerClientPrivate;