Qt Designer: Fix mode switching position logic for multiple screens

The logic tries to maintain the relative form positions when switching
from top level to docked, but used the primary screen as a reference
point. This caused the forms to be out of the docked area when on a
secondary screen.

To fix this, use the widget's screen to calculate the position.

Task-number: QTBUG-120236
Pick-to: 6.6
Change-Id: I51856cdedd6a3f2c2ec73d94c0f726c04caaabca
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
(cherry picked from commit 0c376fd83a8a9c0853d50753ee677fd40235d208)

2 files changed, 11 insertions, 13 deletions

diff --git a/src/designer/src/designer/qdesigner_workbench.cpp b/src/designer/src/designer/qdesigner_workbench.cpp
index 870eee753..8a6ae3c80 100644
--- a/src/designer/src/designer/qdesigner_workbench.cpp
+++ b/src/designer/src/designer/qdesigner_workbench.cpp
@@ -73,9 +73,9 @@ static QDockWidget *dockWidgetOf(const QWidget *w)
 }
 
 // ------------ QDesignerWorkbench::Position
-QDesignerWorkbench::Position::Position(const QMdiSubWindow *mdiSubWindow, const QPoint &mdiAreaOffset) :
+QDesignerWorkbench::Position::Position(const QMdiSubWindow *mdiSubWindow) :
     m_minimized(mdiSubWindow->isShaded()),
-    m_position(mdiSubWindow->pos() + mdiAreaOffset)
+    m_position(mdiSubWindow->pos() + mdiSubWindow->mdiArea()->pos())
 {
 }
 
@@ -85,12 +85,12 @@ QDesignerWorkbench::Position::Position(const QDockWidget *dockWidget) :
 {
 }
 
-QDesignerWorkbench::Position::Position(const QWidget *topLevelWindow, const QPoint &desktopTopLeft)
+QDesignerWorkbench::Position::Position(const QWidget *topLevelWindow)
 {
-    const QWidget *window =topLevelWindow->window ();
+    const QWidget *window = topLevelWindow->window();
     Q_ASSERT(window);
     m_minimized = window->isMinimized();
-    m_position = window->pos() - desktopTopLeft;
+    m_position = window->pos() - window->screen()->availableGeometry().topLeft();
 }
 
 void QDesignerWorkbench::Position::applyTo(QMdiSubWindow *mdiSubWindow,
@@ -247,19 +247,17 @@ void QDesignerWorkbench::saveGeometriesForModeChange()
     case NeutralMode:
         break;
     case TopLevelMode: {
-        const QPoint desktopOffset = QGuiApplication::primaryScreen()->availableGeometry().topLeft();
         for (QDesignerToolWindow *tw : std::as_const(m_toolWindows))
-            m_Positions.insert(tw, Position(tw, desktopOffset));
+            m_Positions.insert(tw, Position(tw));
         for (QDesignerFormWindow *fw : std::as_const(m_formWindows))
-            m_Positions.insert(fw,  Position(fw, desktopOffset));
+            m_Positions.insert(fw, Position(fw));
     }
         break;
     case DockedMode: {
-        const QPoint mdiAreaOffset = m_dockedMainWindow->mdiArea()->pos();
         for (QDesignerToolWindow *tw : std::as_const(m_toolWindows))
             m_Positions.insert(tw, Position(dockWidgetOf(tw)));
         for (QDesignerFormWindow *fw : std::as_const(m_formWindows))
-            m_Positions.insert(fw, Position(mdiSubWindowOf(fw), mdiAreaOffset));
+            m_Positions.insert(fw, Position(mdiSubWindowOf(fw)));
     }
         break;
     }
diff --git a/src/designer/src/designer/qdesigner_workbench.h b/src/designer/src/designer/qdesigner_workbench.h
index 8c60df9dc..171c5b6fe 100644
--- a/src/designer/src/designer/qdesigner_workbench.h
+++ b/src/designer/src/designer/qdesigner_workbench.h
@@ -148,9 +148,9 @@ private:
     // interface modes.
     class Position {
     public:
-        Position(const QDockWidget *dockWidget);
-        Position(const QMdiSubWindow *mdiSubWindow, const QPoint &mdiAreaOffset);
-        Position(const QWidget *topLevelWindow, const QPoint &desktopTopLeft);
+        explicit Position(const QDockWidget *dockWidget);
+        explicit Position(const QMdiSubWindow *mdiSubWindow);
+        explicit Position(const QWidget *topLevelWindow);
 
         void applyTo(QMdiSubWindow *mdiSubWindow, const QPoint &mdiAreaOffset) const;
         void applyTo(QWidget *topLevelWindow, const QPoint &desktopTopLeft) const;