Re #4282. Fix the MantidMatrix dependency issue

Code/Mantid/MantidPlot/src/MdiSubWindow.cpp

@@ -164,8 +164,8 @@ void MdiSubWindow::closeEvent( QCloseEvent *e )
 
   switch(result)
   {
-  case 0:
-    if (widget()->close())
+  case 0: // close
+    if (!widget() || widget()->close())
     {
       e->accept();
       emit closedWindow(this);
@@ -178,12 +178,12 @@ void MdiSubWindow::closeEvent( QCloseEvent *e )
     }
     break;
 
-  case 1:
+  case 1: // hide
     e->ignore();
     emit hiddenWindow(this);
     break;
 
-  case 2:
+  case 2: // cancel
     e->ignore();
     break;
   }
@@ -475,6 +475,11 @@ d_app(appWindow)
   setAttribute(Qt::WA_DeleteOnClose, false);
 }
 
+FloatingWindow::~FloatingWindow()
+{
+  //std::cerr << "Deleted FloatingWindow\n";
+}
+
 /**
  * Catch the WindowActivate event to tell ApplicationWindow that it's activated
  */
@@ -513,7 +518,10 @@ bool FloatingWindow::event(QEvent * e)
   }
   else if (e->type() == QEvent::Close)
   {
-    d_app->removeFloatingWindow(this);
+    if (widget() && widget()->close())
+    {
+      d_app->removeFloatingWindow(this);
+    }
   }
   return QMainWindow::event(e);
 }

Code/Mantid/MantidPlot/src/MdiSubWindow.h

@@ -91,9 +91,15 @@ class MdiSubWindowParent_t: public QWidget
  *
  * These are the main objects of every Qtiplot project.
  * All content (apart from the directory structure) is managed by subclasses of MdiSubWindow.
+ * 
+ * With introduction of floating windows this class is no longer a sub-window (with window title and system menu)
+ * but rather the internal widget of a QMdiSubWindow or a FloatingWindow. The outer window can be changed between
+ * FloatingWindow and QMdiSubWindow at runtime using ApplicationWindow::changeToFloating(...) and
+ * ApplicationWindow::changeToDocked(...) methods. MdiSubWindow overrides show(), hide(), and close() methods so that the 
+ * corresponding events are passed to the outer window.
  *
- * \section future Future Plans
- * Rename to Aspect.
+ * MdiSubWindow can serve as a wrapper for another widget. Use MdiSubWindow::setWidget(...) to set its internal widget.
+ * In this case if close event needs to be processed override closeEvent(...) of the internal widget.
  *
  * \sa Folder, ApplicationWindow
  */
@@ -278,6 +284,7 @@ class FloatingWindow: public QMainWindow
   Q_OBJECT
 public:
   FloatingWindow(ApplicationWindow* appWindow, Qt::WindowFlags f = 0);
+  ~FloatingWindow();
   void setStaysOnTopFlag();
   void removeStaysOnTopFlag();
   MdiSubWindow* mdiSubWindow() {return static_cast<MdiSubWindow*>(widget());}