diff --git a/src/plugins/projectexplorer/gcctoolchain.cpp b/src/plugins/projectexplorer/gcctoolchain.cpp
index e8a4f2eef3c..91072330489 100644
--- a/src/plugins/projectexplorer/gcctoolchain.cpp
+++ b/src/plugins/projectexplorer/gcctoolchain.cpp
@@ -302,9 +302,14 @@ Abi GccToolChain::targetAbi() const
 
 void GccToolChain::setTargetAbi(const Abi &abi)
 {
+    if (abi == m_targetAbi)
+        return;
+
     updateSupportedAbis();
-    if (m_supportedAbis.contains(abi))
+    if (m_supportedAbis.contains(abi)) {
         m_targetAbi = abi;
+        toolChainUpdated();
+    }
 }
 
 QList<Abi> GccToolChain::supportedAbis() const
@@ -348,7 +353,10 @@ void GccToolChain::addToEnvironment(Utils::Environment &env) const
 
 void GccToolChain::setDebuggerCommand(const QString &d)
 {
+    if (m_debuggerCommand == d)
+        return;
     m_debuggerCommand = d;
+    toolChainUpdated();
 }
 
 QString GccToolChain::debuggerCommand() const
@@ -385,7 +393,7 @@ void GccToolChain::setCompilerPath(const QString &path)
         if (displayName() == typeName())
             setDisplayName(defaultDisplayName());
     }
-    updateId();
+    updateId(); // Will trigger toolChainUpdated()!
 }
 
 QString GccToolChain::compilerPath() const
diff --git a/src/plugins/projectexplorer/msvctoolchain.cpp b/src/plugins/projectexplorer/msvctoolchain.cpp
index e807abb6760..6f17dc57e0e 100644
--- a/src/plugins/projectexplorer/msvctoolchain.cpp
+++ b/src/plugins/projectexplorer/msvctoolchain.cpp
@@ -435,7 +435,10 @@ QString MsvcToolChain::makeCommand() const
 
 void MsvcToolChain::setDebuggerCommand(const QString &d)
 {
+    if (m_debuggerCommand == d)
+        return;
     m_debuggerCommand = d;
+    toolChainUpdated();
 }
 
 QString MsvcToolChain::debuggerCommand() const
diff --git a/src/plugins/projectexplorer/toolchain.cpp b/src/plugins/projectexplorer/toolchain.cpp
index 6bc98f111e3..c8dce8ee0a4 100644
--- a/src/plugins/projectexplorer/toolchain.cpp
+++ b/src/plugins/projectexplorer/toolchain.cpp
@@ -32,6 +32,9 @@
 **************************************************************************/
 
 #include "toolchain.h"
+
+#include "toolchainmanager.h"
+
 #include <extensionsystem/pluginmanager.h>
 #include <utils/environment.h>
 
@@ -90,9 +93,13 @@ QString ToolChain::displayName() const
     return m_d->m_displayName;
 }
 
-void ToolChain::setDisplayName(const QString &name) const
+void ToolChain::setDisplayName(const QString &name)
 {
+    if (m_d->m_displayName == name)
+        return;
+
     m_d->m_displayName = name;
+    toolChainUpdated();
 }
 
 bool ToolChain::isAutoDetected() const
@@ -143,12 +150,24 @@ QVariantMap ToolChain::toMap() const
 void ToolChain::setId(const QString &id)
 {
     Q_ASSERT(!id.isEmpty());
+    if (m_d->m_id == id)
+        return;
+
     m_d->m_id = id;
+    toolChainUpdated();
+}
+
+void ToolChain::toolChainUpdated()
+{
+    ToolChainManager::instance()->notifyAboutUpdate(this);
 }
 
 void ToolChain::setAutoDetected(bool autodetect)
 {
+    if (m_d->m_autodetect == autodetect)
+        return;
     m_d->m_autodetect = autodetect;
+    toolChainUpdated();
 }
 
 bool ToolChain::fromMap(const QVariantMap &data)
diff --git a/src/plugins/projectexplorer/toolchain.h b/src/plugins/projectexplorer/toolchain.h
index 640b450b174..98d32ea00f5 100644
--- a/src/plugins/projectexplorer/toolchain.h
+++ b/src/plugins/projectexplorer/toolchain.h
@@ -67,7 +67,7 @@ public:
     virtual ~ToolChain();
 
     QString displayName() const;
-    void setDisplayName(const QString &name) const;
+    void setDisplayName(const QString &name);
 
     bool isAutoDetected() const;
     QString id() const;
@@ -106,6 +106,8 @@ protected:
 
     void setId(const QString &id);
 
+    void toolChainUpdated();
+
     // Make sure to call this method when deriving!
     virtual bool fromMap(const QVariantMap &data);
 
diff --git a/src/plugins/projectexplorer/toolchainmanager.cpp b/src/plugins/projectexplorer/toolchainmanager.cpp
index 91c06b7c43f..271783954da 100644
--- a/src/plugins/projectexplorer/toolchainmanager.cpp
+++ b/src/plugins/projectexplorer/toolchainmanager.cpp
@@ -207,6 +207,13 @@ ToolChain *ToolChainManager::findToolChain(const QString &id) const
     return 0;
 }
 
+void ToolChainManager::notifyAboutUpdate(ProjectExplorer::ToolChain *tc)
+{
+    if (!tc || !m_d->m_toolChains.contains(tc))
+        return;
+    emit toolChainUpdated(tc);
+}
+
 void ToolChainManager::registerToolChain(ToolChain *tc)
 {
     if (!tc || m_d->m_toolChains.contains(tc))
diff --git a/src/plugins/projectexplorer/toolchainmanager.h b/src/plugins/projectexplorer/toolchainmanager.h
index 5b030756def..b43f3f1752a 100644
--- a/src/plugins/projectexplorer/toolchainmanager.h
+++ b/src/plugins/projectexplorer/toolchainmanager.h
@@ -78,6 +78,8 @@ signals:
     void toolChainAdded(ProjectExplorer::ToolChain *);
     // Tool chain is still valid when this call happens!
     void toolChainRemoved(ProjectExplorer::ToolChain *);
+    // Tool chain was updated.
+    void toolChainUpdated(ProjectExplorer::ToolChain *);
 
 private:
     explicit ToolChainManager(QObject *parent = 0);
@@ -87,12 +89,15 @@ private:
     void restoreToolChains();
     void restoreToolChains(const QString &fileName, bool autoDetected = false);
 
+    void notifyAboutUpdate(ProjectExplorer::ToolChain *);
+
 
     Internal::ToolChainManagerPrivate *const m_d;
 
     static ToolChainManager *m_instance;
 
     friend class ProjectExplorerPlugin;
+    friend class ToolChain;
 };
 
 } // namespace ProjectExplorer
diff --git a/src/plugins/qt4projectmanager/qt-maemo/maemotoolchain.cpp b/src/plugins/qt4projectmanager/qt-maemo/maemotoolchain.cpp
index d8bbfad3538..d1f49ed9100 100644
--- a/src/plugins/qt4projectmanager/qt-maemo/maemotoolchain.cpp
+++ b/src/plugins/qt4projectmanager/qt-maemo/maemotoolchain.cpp
@@ -171,7 +171,7 @@ void MaemoToolChain::setQtVersionId(int id)
     if (id < 0) {
         m_targetAbi = ProjectExplorer::Abi();
         m_qtVersionId = -1;
-        updateId();
+        updateId(); // Will trigger toolChainUpdated()!
         return;
     }
 
@@ -192,7 +192,7 @@ void MaemoToolChain::setQtVersionId(int id)
     Q_ASSERT(version->qtAbis().count() == 1);
     m_targetAbi = version->qtAbis().at(0);
 
-    updateId();
+    updateId(); // Will trigger toolChainUpdated()!
     setDisplayName(MaemoToolChainFactory::tr("Maemo GCC for %1").arg(version->displayName()));
 }
 
diff --git a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp
index ad2a058350c..cd5cd2ba963 100644
--- a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp
+++ b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.cpp
@@ -248,7 +248,10 @@ bool RvctToolChain::operator ==(const ToolChain &other) const
 
 void RvctToolChain::setEnvironmentChanges(const QList<Utils::EnvironmentItem> &changes)
 {
+    if (m_environmentChanges == changes)
+        return;
     m_environmentChanges = changes;
+    toolChainUpdated();
 }
 
 QList<Utils::EnvironmentItem> RvctToolChain::environmentChanges() const
@@ -263,7 +266,7 @@ void RvctToolChain::setCompilerPath(const QString &path)
 
     m_compilerPath = path;
     m_version.reset();
-    updateId();
+    updateId(); // Will trigger toolChainUpdated()!
 }
 
 QString RvctToolChain::compilerPath() const
@@ -273,7 +276,10 @@ QString RvctToolChain::compilerPath() const
 
 void RvctToolChain::setDebuggerCommand(const QString &d)
 {
+    if (m_debuggerCommand == d)
+        return;
     m_debuggerCommand = d;
+    toolChainUpdated();
 }
 
 QString RvctToolChain::debuggerCommand() const
@@ -283,7 +289,10 @@ QString RvctToolChain::debuggerCommand() const
 
 void RvctToolChain::setArmVersion(RvctToolChain::ArmVersion av)
 {
+    if (m_armVersion == av)
+        return;
     m_armVersion = av;
+    toolChainUpdated();
 }
 
 RvctToolChain::ArmVersion RvctToolChain::armVersion() const
@@ -293,7 +302,10 @@ RvctToolChain::ArmVersion RvctToolChain::armVersion() const
 
 void RvctToolChain::setVersion(const RvctVersion &v) const
 {
+    if (m_version == v)
+        return;
     m_version = v;
+    // Internal use only! No need to call toolChainUpdated()!
 }
 
 ProjectExplorer::ToolChainConfigWidget *RvctToolChain::configurationWidget()
diff --git a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h
index 64eea5c439b..40efbac9a40 100644
--- a/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h
+++ b/src/plugins/qt4projectmanager/qt-s60/rvcttoolchain.h
@@ -66,6 +66,13 @@ public:
         bool isNull() { return majorVersion == 0 && minorVersion == 0 && build == 0; }
         void reset() { majorVersion = 0; minorVersion = 0; build = 0; }
 
+        bool operator ==(const RvctVersion &other) const
+        {
+            return majorVersion == other.majorVersion
+                    && minorVersion == other.minorVersion
+                    && build == other.build;
+        }
+
         int majorVersion;
         int minorVersion;
         int build;
@@ -101,8 +108,6 @@ public:
     void setArmVersion(ArmVersion);
     ArmVersion armVersion() const;
 
-    void setVersion(const RvctVersion &v) const;
-
     ProjectExplorer::ToolChainConfigWidget *configurationWidget();
     ProjectExplorer::ToolChain *clone() const;
 
@@ -111,6 +116,7 @@ public:
 
 private:
     void updateId();
+    void setVersion(const RvctVersion &v) const;
 
     explicit RvctToolChain(bool autodetected = false);
     RvctToolChain(const RvctToolChain &);
diff --git a/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp b/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp
index d64bb50094a..c6893ac7558 100644
--- a/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp
+++ b/src/plugins/qt4projectmanager/qt-s60/winscwtoolchain.cpp
@@ -250,7 +250,10 @@ bool WinscwToolChain::fromMap(const QVariantMap &data)
 
 void WinscwToolChain::setSystemIncludePathes(const QStringList &pathes)
 {
+    if (m_systemIncludePathes == pathes)
+        return;
     m_systemIncludePathes = pathes;
+    toolChainUpdated();
 }
 
 QStringList WinscwToolChain::systemIncludePathes() const
@@ -260,7 +263,10 @@ QStringList WinscwToolChain::systemIncludePathes() const
 
 void WinscwToolChain::setSystemLibraryPathes(const QStringList &pathes)
 {
+    if (m_systemLibraryPathes == pathes)
+        return;
     m_systemLibraryPathes = pathes;
+    toolChainUpdated();
 }
 
 QStringList WinscwToolChain::systemLibraryPathes() const
@@ -274,7 +280,7 @@ void WinscwToolChain::setCompilerPath(const QString &path)
         return;
 
     m_compilerPath = path;
-    updateId();
+    updateId(); // Will trigger topolChainUpdated()!
 }
 
 QString WinscwToolChain::compilerPath() const