diff --git a/qt/widgets/common/CMakeLists.txt b/qt/widgets/common/CMakeLists.txt
index af9fe243e90ffecf94f04212ba364c9d28670e23..6352a20f393b245d04e7e177274acd8f0a5a85ae 100644
--- a/qt/widgets/common/CMakeLists.txt
+++ b/qt/widgets/common/CMakeLists.txt
@@ -17,6 +17,7 @@ set ( QT5_SRC_FILES
   src/FlowLayout.cpp
   src/FunctionBrowser.cpp
   src/GenericDialog.cpp
+  # Used in Qt5 by LoadDialog
   src/HelpWindow.cpp
   src/InterfaceFactory.cpp
   src/InterfaceManager.cpp
@@ -25,37 +26,41 @@ set ( QT5_SRC_FILES
   src/ManageUserDirectories.cpp
   src/MantidDesktopServices.cpp
   src/MantidHelpInterface.cpp
-  src/MantidHelpWindow.cpp
   src/MantidTreeModel.cpp
   src/MantidTreeWidget.cpp
   src/MantidTreeWidgetItem.cpp
+  # todo comment
   src/MantidWidget.cpp
+  # todo comment
   src/MantidWSIndexDialog.cpp
   src/Message.cpp
   src/MessageDisplay.cpp
   src/MWRunFiles.cpp
   src/OptionsPropertyWidget.cpp
-  # check if used in QT5 and if so where
-  src/PeriodicTableWidget.cpp
-  # check if used in QT5 and if so where
+  # used in QT5: GetNegMuMuonicXRDDialog
+
+  # used in QT5: in WorkspaceTreeWidget for getIcon
   src/pixmaps.cpp
   src/PluginLibraries.cpp
-  # check if used in QT5 and if so where
-  src/pqHelpWindow.cxx
   src/ProcessingAlgoWidget.cpp
   src/PropertyWidget.cpp
   src/PropertyWidgetFactory.cpp
-  # check if used in QT5 and if so where
+  # used in QT5: used in many files - MantidWidget/MantidDialog
   src/PythonRunner.cpp
   src/QtSignalChannel.cpp
-  # check if used in QT5 and if so where
+  # used in QT5: used by UserFunctionDialog
   src/RenameParDialog.cpp
   src/ScriptEditor.cpp
   src/SelectFunctionDialog.cpp
   src/TextPropertyWidget.cpp
+  # used in QT5: by FunctionBrowser
   src/UserFunctionDialog.cpp
+
+  # todo comment
   src/UserSubWindow.cpp
+  # todo comment
   src/VatesViewerInterface.cpp
+  # todo comment
   src/WidgetScrollbarDecorator.cpp
   src/WorkspaceIcons.cpp
   src/WorkspaceObserver.cpp
@@ -104,7 +109,6 @@ set ( QT5_MOC_FILES
   inc/MantidQtWidgets/Common/ListPropertyWidget.h
   inc/MantidQtWidgets/Common/ManageUserDirectories.h
   inc/MantidQtWidgets/Common/MantidHelpInterface.h
-  inc/MantidQtWidgets/Common/MantidHelpWindow.h
   inc/MantidQtWidgets/Common/MantidTreeModel.h
   inc/MantidQtWidgets/Common/MantidTreeWidget.h
   inc/MantidQtWidgets/Common/MantidWidget.h
@@ -112,8 +116,6 @@ set ( QT5_MOC_FILES
   inc/MantidQtWidgets/Common/MessageDisplay.h
   inc/MantidQtWidgets/Common/MWRunFiles.h
   inc/MantidQtWidgets/Common/OptionsPropertyWidget.h
-  inc/MantidQtWidgets/Common/PeriodicTableWidget.h
-  inc/MantidQtWidgets/Common/pqHelpWindow.h
   inc/MantidQtWidgets/Common/ProcessingAlgoWidget.h
   inc/MantidQtWidgets/Common/PropertyWidget.h
   inc/MantidQtWidgets/Common/PythonRunner.h
@@ -182,9 +184,8 @@ set ( QT5_INC_FILES
 set ( QT5_UI_FILES
   inc/MantidQtWidgets/Common/DataSelector.ui
   inc/MantidQtWidgets/Common/MWRunFiles.ui
-  inc/MantidQtWidgets/Common/PeriodicTableWidget.ui
-  inc/MantidQtWidgets/Common/pqHelpWindow.ui
   inc/MantidQtWidgets/Common/ProcessingAlgoWidget.ui
+  inc/MantidQtWidgets/Common/RenameParDialog.ui
   inc/MantidQtWidgets/Common/SelectFunctionDialog.ui
 )
 
@@ -312,7 +313,8 @@ set ( SRC_FILES
   src/MuonFitDataSelector.cpp
   src/MuonFitPropertyBrowser.cpp
   src/MuonFunctionBrowser.cpp
-  src/PeriodicTableWidget.cpp
+  # todo check if it can be removed from qt4
+
   src/ProcessingAlgoWidget.cpp
   src/ProgressableView.cpp
   src/ProjectSavePresenter.cpp
@@ -421,7 +423,8 @@ set ( MOC_FILES
   inc/MantidQtWidgets/Common/MuonFitPropertyBrowser.h
   inc/MantidQtWidgets/Common/MuonFunctionBrowser.h
   inc/MantidQtWidgets/Common/MWDiag.h
-  inc/MantidQtWidgets/Common/PeriodicTableWidget.h
+  # todo check if it can be removed from qt4
+
   inc/MantidQtWidgets/Common/pqHelpWindow.h
   inc/MantidQtWidgets/Common/PropertyHandler.h
   inc/MantidQtWidgets/Common/ProcessingAlgoWidget.h
@@ -630,7 +633,8 @@ set ( UI_FILES
   inc/MantidQtWidgets/Common/SlicingAlgorithmDialog.ui
   inc/MantidQtWidgets/Common/SlitCalculator.ui
   inc/MantidQtWidgets/Common/UserFunctionDialog.ui
-  inc/MantidQtWidgets/Common/PeriodicTableWidget.ui
+  # todo check if it can be removed from qt4
+
   inc/MantidQtWidgets/Common/pqHelpWindow.ui
 )
 
diff --git a/qt/widgets/plugins/algorithm_dialogs/CMakeLists.txt b/qt/widgets/plugins/algorithm_dialogs/CMakeLists.txt
index bce541bbaabb0cfae568017e9d1994710ed1ae73..5b69ac8272225245335b8d5dcfe963cfd04a6635 100644
--- a/qt/widgets/plugins/algorithm_dialogs/CMakeLists.txt
+++ b/qt/widgets/plugins/algorithm_dialogs/CMakeLists.txt
@@ -9,6 +9,7 @@ set ( SRC_FILES src/CatalogPublishDialog.cpp
                 src/LOQScriptInputDialog.cpp
                 src/MantidGLWidget.cpp
                 src/GetNegMuMuonicXRDDialog.cpp
+                src/PeriodicTableWidget.cpp
                 src/PlotAsymmetryByLogValueDialog.cpp
                 src/SampleShapeHelpers.cpp
                 src/SmoothNeighboursDialog.cpp
@@ -16,25 +17,26 @@ set ( SRC_FILES src/CatalogPublishDialog.cpp
 )
 
 set ( MOC_FILES inc/MantidQtWidgets/Plugins/AlgorithmDialogs/CatalogPublishDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/CreateSampleShapeDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/ConvertTableToMatrixWorkspaceDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/StartLiveDataDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/FitDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadDAEDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadRawDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LOQScriptInputDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/MantidGLWidget.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/GetNegMuMuonicXRDDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PlotAsymmetryByLogValueDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/SampleShapeHelpers.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/SmoothNeighboursDialog.h
-                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/SortTableWorkspaceDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/CreateSampleShapeDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/ConvertTableToMatrixWorkspaceDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/StartLiveDataDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/FitDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadDAEDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadRawDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LOQScriptInputDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/MantidGLWidget.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/GetNegMuMuonicXRDDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PlotAsymmetryByLogValueDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/SampleShapeHelpers.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/SmoothNeighboursDialog.h
+inc/MantidQtWidgets/Plugins/AlgorithmDialogs/SortTableWorkspaceDialog.h
 )
 
 # Include files aren't required, but this makes them appear in Visual Studio
 set ( INC_FILES
-    ${MOC_FILES}
+${MOC_FILES}
 )
 
 set ( UI_FILES inc/MantidQtWidgets/Plugins/AlgorithmDialogs/CatalogPublishDialog.ui
@@ -42,6 +44,7 @@ set ( UI_FILES inc/MantidQtWidgets/Plugins/AlgorithmDialogs/CatalogPublishDialog
                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/ConvertTableToMatrixWorkspaceDialog.ui
                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/DiagScriptInputDialog.ui
                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LOQScriptInputDialog.ui
+               inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.ui
                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PlotAsymmetryByLogValueDialog.ui
                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/LoadDialog.ui
                inc/MantidQtWidgets/Plugins/AlgorithmDialogs/StartLiveDataDialog.ui
diff --git a/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/GetNegMuMuonicXRDDialog.h b/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/GetNegMuMuonicXRDDialog.h
index 60bd93a8100be9c2d1cb8d2aef2424cc5a72738a..08e60b597d38e5d88720f6e917e51d7e573fc89b 100644
--- a/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/GetNegMuMuonicXRDDialog.h
+++ b/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/GetNegMuMuonicXRDDialog.h
@@ -2,7 +2,7 @@
 #define MANTIDQT_CUSTOM_DIALOGS_GETNEGMUMUONICXRD_H_
 
 #include "MantidQtWidgets/Common/AlgorithmDialog.h"
-#include "MantidQtWidgets/Common/PeriodicTableWidget.h"
+#include "MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.h"
 #include <QDoubleSpinBox>
 namespace MantidQt {
 
diff --git a/qt/widgets/common/inc/MantidQtWidgets/Common/PeriodicTableWidget.h b/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.h
similarity index 98%
rename from qt/widgets/common/inc/MantidQtWidgets/Common/PeriodicTableWidget.h
rename to qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.h
index dbcad0c852bf27d354fecc03f43651a7d6efe096..81c7fe18215360ebdc44ec173ad0a89da69e52be 100644
--- a/qt/widgets/common/inc/MantidQtWidgets/Common/PeriodicTableWidget.h
+++ b/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.h
@@ -32,7 +32,7 @@
   Code Documentation is available at: <http://doxygen.mantidproject.org>
 */
 
-class EXPORT_OPT_MANTIDQT_COMMON PeriodicTableWidget : public QWidget {
+class PeriodicTableWidget : public QWidget {
   Q_OBJECT
 
 public:
diff --git a/qt/widgets/common/inc/MantidQtWidgets/Common/PeriodicTableWidget.ui b/qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.ui
similarity index 100%
rename from qt/widgets/common/inc/MantidQtWidgets/Common/PeriodicTableWidget.ui
rename to qt/widgets/plugins/algorithm_dialogs/inc/MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.ui
diff --git a/qt/widgets/common/src/PeriodicTableWidget.cpp b/qt/widgets/plugins/algorithm_dialogs/src/PeriodicTableWidget.cpp
similarity index 99%
rename from qt/widgets/common/src/PeriodicTableWidget.cpp
rename to qt/widgets/plugins/algorithm_dialogs/src/PeriodicTableWidget.cpp
index 3de366e03bc751c734fb17fdb6fd2796f55d93f6..b06fff4334ddb90bd9e13f76e8f6818337315eb9 100644
--- a/qt/widgets/common/src/PeriodicTableWidget.cpp
+++ b/qt/widgets/plugins/algorithm_dialogs/src/PeriodicTableWidget.cpp
@@ -1,4 +1,4 @@
-#include "MantidQtWidgets/Common/PeriodicTableWidget.h"
+#include "MantidQtWidgets/Plugins/AlgorithmDialogs/PeriodicTableWidget.h"
 #include <QVector>
 
 /**