feat: add preferred auto-hide sidebar location per dock widget (#829)

Add preferredAutoHideSideBarLocation property to CDockWidget that allows
applications to specify where a widget should be pinned, overriding
geometry-based detection. When unpinning, widgets with the same preferred
location merge as tabs instead of creating new splits.

Default is SideBarNone (existing geometry-based behavior preserved).

src/AutoHideDockContainer.cpp

@@ -415,7 +415,31 @@ void CAutoHideDockContainer::moveContentsToParent()
 	// to the user and he does not have to search where the widget was inserted.
 	d->DockWidget->setDockArea(nullptr);
 	auto DockContainer = dockContainer();
-	DockContainer->addDockWidget(d->getDockWidgetArea(d->SideTabBarArea), d->DockWidget);
+	auto targetArea = d->getDockWidgetArea(d->SideTabBarArea);
+
+	// If the widget has a preferred auto-hide location, try to find an existing
+	// opened dock area that contains a widget with the same preferred location
+	// and merge as a tab instead of creating a new split.
+	auto preferred = d->DockWidget->preferredAutoHideSideBarLocation();
+	if (preferred != SideBarNone)
+	{
+		for (auto area : DockContainer->openedDockAreas())
+		{
+			if (!area || area->isAutoHide()) continue;
+			// Check if any widget in this area has the same preferred location
+			for (auto dw : area->dockWidgets())
+			{
+				if (dw && dw->preferredAutoHideSideBarLocation() == preferred)
+				{
+					DockContainer->addDockWidget(CenterDockWidgetArea,
+						d->DockWidget, area);
+					return;
+				}
+			}
+		}
+	}
+
+	DockContainer->addDockWidget(targetArea, d->DockWidget);
 }
 
 

src/DockWidget.cpp

@@ -96,7 +96,8 @@ struct DockWidgetPrivate
 	WidgetFactory* Factory = nullptr;
 	QPointer<CAutoHideTab> SideTabWidget;
 	CDockWidget::eToolBarStyleSource ToolBarStyleSource = CDockWidget::ToolBarStyleFromDockManager;
-	
+	SideBarLocation PreferredAutoHideSideBarLocation = SideBarNone;
+
 	/**
 	 * Private data constructor
 	 */
@@ -654,6 +655,20 @@ SideBarLocation CDockWidget::autoHideLocation() const
 }
 
 
+//============================================================================
+void CDockWidget::setPreferredAutoHideSideBarLocation(SideBarLocation Location)
+{
+	d->PreferredAutoHideSideBarLocation = Location;
+}
+
+
+//============================================================================
+SideBarLocation CDockWidget::preferredAutoHideSideBarLocation() const
+{
+	return d->PreferredAutoHideSideBarLocation;
+}
+
+
 //============================================================================
 bool CDockWidget::isFloating() const
 {
@@ -1337,7 +1352,15 @@ void CDockWidget::setAutoHide(bool Enable, SideBarLocation Location, int TabInde
 	}
 	else
 	{
-		auto area = (SideBarNone == Location) ? DockArea->calculateSideTabBarArea() : Location;
+		auto area = Location;
+		if (SideBarNone == area && d->PreferredAutoHideSideBarLocation != SideBarNone)
+		{
+			area = d->PreferredAutoHideSideBarLocation;
+		}
+		else if (SideBarNone == area)
+		{
+			area = DockArea->calculateSideTabBarArea();
+		}
 		dockContainer()->createAndSetupAutoHideContainer(area, this, TabIndex);
 	}
 }

src/DockWidget.h

@@ -422,6 +422,22 @@ public:
      */
     SideBarLocation autoHideLocation() const;
 
+    /**
+     * Sets the preferred auto-hide sidebar location for this dock widget.
+     * When set to a value other than SideBarNone, the pin button will place
+     * this widget in the specified sidebar instead of using geometry-based
+     * detection. When unpinning, widgets with the same preferred location
+     * will be merged as tabs in the same dock area.
+     * Set to SideBarNone (default) to use the original geometry-based behavior.
+     */
+    void setPreferredAutoHideSideBarLocation(SideBarLocation Location);
+
+    /**
+     * Returns the preferred auto-hide sidebar location, or SideBarNone
+     * if no preference is set (geometry-based detection will be used).
+     */
+    SideBarLocation preferredAutoHideSideBarLocation() const;
+
     /**
      * This property holds whether the dock widget is floating.
      * A dock widget is only floating, if it is the one and only widget inside