Debugger: Fix switching threads using the threadsview

Amends 9f9c7230.

Change-Id: I58193f2d159bb6b839762b0cf02ec8fc4a9df48a
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/debuggerengine.cpp

@@ -397,11 +397,7 @@ public:
     void selectThread(int index)
     {
         const Thread thread = m_engine->threadsHandler()->rootItem()->childAt(index);
-        QTC_ASSERT(thread, return);
+        m_engine->doSelectThread(thread);
-        // For immediate visual feedback.
-        m_engine->threadsHandler()->setCurrentThread(thread);
-        // Initiate the actual switching in the debugger backend.
-        m_engine->selectThread(thread);
     }
 
     void handleOperateByInstructionTriggered(bool on)
@@ -2082,6 +2078,16 @@ void DebuggerEngine::assignValueInDebugger(WatchItem *,
 {
 }
 
+void DebuggerEngine::doSelectThread(const Thread &thread)
+{
+    QTC_ASSERT(thread, return);
+    // For immediate visual feedback.
+    d->m_threadsHandler.setCurrentThread(thread);
+    d->m_threadBox->setCurrentIndex(d->m_threadsHandler.currentThreadIndex());
+    // Initiate the actual switching in the debugger backend.
+    selectThread(thread);
+}
+
 void DebuggerEngine::handleRecordReverse(bool record)
 {
     executeRecordReverse(record);

src/plugins/debugger/debuggerengine.h

@@ -317,6 +317,7 @@ public:
     virtual void assignValueInDebugger(WatchItem *item,
         const QString &expr, const QVariant &value);
     virtual void selectThread(const Internal::Thread &thread) = 0;
+    void doSelectThread(const Internal::Thread &thread);
 
     virtual void executeRecordReverse(bool) {}
     virtual void executeReverse(bool) {}

src/plugins/debugger/threadshandler.cpp

@@ -240,7 +240,8 @@ bool ThreadsHandler::setData(const QModelIndex &idx, const QVariant &data, int r
 {
     if (role == BaseTreeView::ItemActivatedRole) {
         const Thread thread = itemForIndexAtLevel<1>(idx);
-        m_engine->selectThread(thread);
+        if (thread != m_currentThread)
+            m_engine->doSelectThread(thread);
         return true;
     }