Allow disabling a specific tab from being dragged

* Also cancels any re-arrangements that involve that tab (mostly useful
  for a fixed tab at the start of the tab list).

qrenderdoc/3rdparty/toolwindowmanager/ToolWindowManager.h

@@ -109,6 +109,8 @@ public:
     DisallowUserDocking = 0x1,
     //! Hides the close button on the tab for this tool window
     HideCloseButton = 0x2,
+    //! Disable the user being able to drag this tab in the tab bar, to rearrange
+    DisableDraggableTab = 0x4,
   };
 
   //! Type of AreaReference.

qrenderdoc/3rdparty/toolwindowmanager/ToolWindowManagerArea.cpp

@@ -34,11 +34,14 @@ ToolWindowManagerArea::ToolWindowManagerArea(ToolWindowManager *manager, QWidget
 {
   m_dragCanStart = false;
   m_tabDragCanStart = false;
+  m_inTabMoved = false;
   setMovable(true);
   setTabsClosable(true);
   setDocumentMode(true);
   tabBar()->installEventFilter(this);
   m_manager->m_areas << this;
+
+  QObject::connect(tabBar(), &QTabBar::tabMoved, this, &ToolWindowManagerArea::tabMoved);
 }
 
 ToolWindowManagerArea::~ToolWindowManagerArea() {
@@ -100,9 +103,18 @@ bool ToolWindowManagerArea::eventFilter(QObject *object, QEvent *event) {
   if (object == tabBar()) {
     if (event->type() == QEvent::MouseButtonPress &&
         qApp->mouseButtons() == Qt::LeftButton) {
+
+      int tabIndex = tabBar()->tabAt(static_cast<QMouseEvent*>(event)->pos());
+
       // can start tab drag only if mouse is at some tab, not at empty tabbar space
-      if (tabBar()->tabAt(static_cast<QMouseEvent*>(event)->pos()) >= 0 ) {
+      if (tabIndex >= 0) {
         m_tabDragCanStart = true;
+
+        if (m_manager->toolWindowProperties(widget(tabIndex)) & ToolWindowManager::DisableDraggableTab) {
+          setMovable(false);
+        } else {
+          setMovable(true);
+        }
       } else {
         m_dragCanStart = true;
       }
@@ -193,3 +205,20 @@ void ToolWindowManagerArea::check_mouse_move() {
     m_manager->startDrag(toolWindows);
   }
 }
+
+void ToolWindowManagerArea::tabMoved(int from, int to) {
+  if(m_inTabMoved) return;
+
+  QWidget *a = widget(from);
+  QWidget *b = widget(to);
+
+  if(!a || !b) return;
+
+  if(m_manager->toolWindowProperties(a) & ToolWindowManager::DisableDraggableTab ||
+     m_manager->toolWindowProperties(b) & ToolWindowManager::DisableDraggableTab)
+  {
+    m_inTabMoved = true;
+    tabBar()->moveTab(to, from);
+    m_inTabMoved = false;
+  }
+}

qrenderdoc/3rdparty/toolwindowmanager/ToolWindowManagerArea.h

@@ -82,6 +82,9 @@ private:
                           // that can be considered as dragging current tab
                           // if the cursor will leave the tab bar area
 
+  bool m_inTabMoved; // if we're in the tabMoved() function (so if we call tabMove to cancel
+                     // the movement, we shouldn't re-check the tabMoved behaviour)
+
   QVariantMap saveState(); // dump contents to variable
   void restoreState(const QVariantMap& data); //restore contents from given variable
 
@@ -91,6 +94,8 @@ private:
   friend class ToolWindowManager;
   friend class ToolWindowManagerWrapper;
 
+private slots:
+  void tabMoved(int from, int to);
 };
 
 #endif // TOOLWINDOWMANAGERAREA_H