Improved tab dragging, added support for undocking if mouse leaves tabbar during tb dragging

Author: githubuser0xFFFF

demo/MainWindow.cpp

@@ -488,7 +488,7 @@ CMainWindow::CMainWindow(QWidget *parent) :
 
     // uncomment the following line if you want to use opaque undocking and
 	// opaque splitter resizing
-    // CDockManager::setConfigFlags(CDockManager::DefaultOpaqueConfig);
+    //CDockManager::setConfigFlags(CDockManager::DefaultOpaqueConfig);
 
     // uncomment the following line if you want a fixed tab width that does
 	// not change if the visibility of the close button changes

src/DockWidgetTab.cpp

@@ -215,6 +215,8 @@ void DockWidgetTabPrivate::moveTab(QMouseEvent* ev)
     QPoint Distance = ev->globalPos() - GlobalDragStartMousePosition;
     Distance.setY(0);
     auto TargetPos = Distance + TabDragStartPosition;
+    TargetPos.rx() = qMax(TargetPos.x(), 0);
+    TargetPos.rx() = qMin(_this->parentWidget()->rect().right() - _this->width() + 1, TargetPos.rx());
     _this->move(TargetPos);
     _this->raise();
 }
@@ -357,19 +359,18 @@ void CDockWidgetTab::mouseMoveEvent(QMouseEvent* ev)
     }
 
     // move tab
-    bool TabOutsideBar = false;
     if (d->isDraggingState(DraggingTab))
     {
         // Moving the tab is always allowed because it does not mean moving the
     	// dock widget around
     	d->moveTab(ev);
-    	TabOutsideBar = (geometry().right() < 0) || (geometry().left() > parentWidget()->rect().right());
     }
 
-
+    auto MappedPos = mapToParent(ev->pos());
+    bool MouseOutsideBar = (MappedPos.x() < 0) || (MappedPos.x() > parentWidget()->rect().right());
     // Maybe a fixed drag distance is better here ?
     int DragDistanceY = qAbs(d->GlobalDragStartMousePosition.y() - ev->globalPos().y());
-    if (DragDistanceY >= CDockManager::startDragDistance() || TabOutsideBar)
+    if (DragDistanceY >= CDockManager::startDragDistance() || MouseOutsideBar)
 	{
 		// If this is the last dock area in a dock container with only
     	// one single dock widget it does not make  sense to move it to a new