Avoid GUI cleanup on a main window being destroyed

ApplicationLibCode/UserInterface/RiuMainWindow.cpp

@@ -190,6 +190,8 @@ RiuMainWindow::RiuMainWindow()
 //--------------------------------------------------------------------------------------------------
 RiuMainWindow::~RiuMainWindow()
 {
+    setBeingDestroyed();
+
     setPdmRoot( nullptr );
 
     if ( m_pdmUiPropertyView )
@@ -329,6 +331,10 @@ void RiuMainWindow::cleanupGuiCaseClose()
 //--------------------------------------------------------------------------------------------------
 void RiuMainWindow::cleanupGuiBeforeProjectClose()
 {
+    // Closing the last window can trigger a project close while this window is being destroyed. Accessing the
+    // GUI of a window being destroyed is not safe.
+    if ( isBeingDestroyed() ) return;
+
     for ( auto v : viewWindows() )
     {
         v->removeWindowFromDock();

ApplicationLibCode/UserInterface/RiuMainWindowBase.cpp

@@ -73,6 +73,7 @@ RiuMainWindowBase::RiuMainWindowBase()
     , m_blockSubWindowActivation( false )
     , m_blockSubWindowProjectTreeSelection( false )
     , m_hasBeenVisible( false )
+    , m_isBeingDestroyed( false )
     , m_windowMenu( nullptr )
 {
     ads::CDockManager::setAutoHideConfigFlags( ads::CDockManager::DefaultAutoHideConfig );
@@ -795,6 +796,22 @@ void RiuMainWindowBase::addDefaultEntriesToWindowsMenu()
     m_windowMenu->addAction( m_maximizeWindowsAction );
 }
 
+//--------------------------------------------------------------------------------------------------
+/// Called when the destructor of a main window starts. Used to avoid operations on a window being destroyed.
+//--------------------------------------------------------------------------------------------------
+void RiuMainWindowBase::setBeingDestroyed()
+{
+    m_isBeingDestroyed = true;
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+bool RiuMainWindowBase::isBeingDestroyed() const
+{
+    return m_isBeingDestroyed;
+}
+
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------

ApplicationLibCode/UserInterface/RiuMainWindowBase.h

@@ -92,6 +92,9 @@ public:
     void setBlockViewSelectionOnSubWindowActivated( bool block );
     bool isBlockingViewSelectionOnSubWindowActivated() const;
 
+    void setBeingDestroyed();
+    bool isBeingDestroyed() const;
+
     ads::CDockManager* dockManager() const;
 
     QString dockWidgetStateString() const;
@@ -167,6 +170,7 @@ private:
     bool m_blockSubWindowActivation;
     bool m_blockSubWindowProjectTreeSelection;
     bool m_hasBeenVisible;
+    bool m_isBeingDestroyed;
 
     ads::CDockManager* m_dockManager;
 };

ApplicationLibCode/UserInterface/RiuPlotMainWindow.cpp

@@ -122,6 +122,8 @@ RiuPlotMainWindow::RiuPlotMainWindow()
 //--------------------------------------------------------------------------------------------------
 RiuPlotMainWindow::~RiuPlotMainWindow()
 {
+    setBeingDestroyed();
+
     m_summaryPlotManagerView->showProperties( nullptr );
     setPdmRoot( nullptr );
 }
@@ -225,6 +227,10 @@ void RiuPlotMainWindow::initializeGuiNewProjectLoaded()
 //--------------------------------------------------------------------------------------------------
 void RiuPlotMainWindow::cleanupGuiBeforeProjectClose()
 {
+    // Closing the last window can trigger a project close while this window is being destroyed. Accessing the
+    // GUI of a window being destroyed is not safe.
+    if ( isBeingDestroyed() ) return;
+
     for ( auto v : viewWindows() )
     {
         v->removeWindowFromDock();