Add option to always show all tabs (#102)

* Add option to always show tabs.

* Disable "Detach" context menu option in tab if there is only one tab in the floating container.

src/DockAreaWidget.cpp

@@ -702,6 +702,11 @@ void CDockAreaWidget::updateTitleBarVisibility()
 		return;
 	}
 
+    if (CDockManager::configFlags().testFlag(CDockManager::AlwaysShowTabs))
+    {
+        return;
+    }
+
 	if (d->TitleBar)
 	{
 		d->TitleBar->setVisible(!Container->isFloating() || !Container->hasTopLevelDockWidget());

src/DockContainerWidget.h

@@ -130,14 +130,6 @@ protected:
 	 */
 	CDockAreaWidget* lastAddedDockAreaWidget(DockWidgetArea area) const;
 
-	/**
-	 * This function returns true if this dock area has only one single
-	 * visible dock widget.
-	 * A top level widget is a real floating widget. Only the isFloating()
-	 * function of top level widgets may returns true.
-	 */
-	bool hasTopLevelDockWidget() const;
-
 	/**
 	 * If hasSingleVisibleDockWidget() returns true, this function returns the
 	 * one and only visible dock widget. Otherwise it returns a nullptr.
@@ -214,6 +206,14 @@ public:
 	 */
 	QList<CDockAreaWidget*> openedDockAreas() const;
 
+    /**
+     * This function returns true if this dock area has only one single
+     * visible dock widget.
+     * A top level widget is a real floating widget. Only the isFloating()
+     * function of top level widgets may returns true.
+     */
+    bool hasTopLevelDockWidget() const;
+
 	/**
 	 * Returns the number of dock areas in this container
 	 */

src/DockManager.h

@@ -156,6 +156,7 @@ public:
 		DragPreviewIsDynamic = 0x0400,///< If opaque undocking is disabled, this flag defines the behavior of the drag preview window, if this flag is enabled, the preview will be adjusted dynamically to the drop area
 		DragPreviewShowsContentPixmap = 0x0800,///< If opaque undocking is disabled, the created drag preview window shows a copy of the content of the dock widget / dock are that is dragged
 		DragPreviewHasWindowFrame = 0x1000,///< If opaque undocking is disabled, then this flag configures if the drag preview is frameless or looks like a real window
+        AlwaysShowTabs = 0x2000,
 		DefaultConfig = ActiveTabHasCloseButton
 		              | DockAreaHasCloseButton
 		              | OpaqueSplitterResize

src/DockWidgetTab.cpp

@@ -426,8 +426,14 @@ void CDockWidgetTab::contextMenuEvent(QContextMenuEvent* ev)
 
 	d->GlobalDragStartMousePosition = ev->globalPos();
 	QMenu Menu(this);
+
+    const bool isFloatable = d->DockWidget->features().testFlag(CDockWidget::DockWidgetFloatable);
+    const bool isNotOnlyTabInContainer =  !d->DockArea->dockContainer()->hasTopLevelDockWidget();
+
+    const bool isDetachable = isFloatable && isNotOnlyTabInContainer;
+
 	auto Action = Menu.addAction(tr("Detach"), this, SLOT(detachDockWidget()));
-	Action->setEnabled(d->DockWidget->features().testFlag(CDockWidget::DockWidgetFloatable));
+    Action->setEnabled(isDetachable);
 	Menu.addSeparator();
 	Action = Menu.addAction(tr("Close"), this, SIGNAL(closeRequested()));
 	Action->setEnabled(isClosable());