diff --git a/adsConfig.cmake b/adsConfig.cmake
index d006a3f..9f9b307 100644
--- a/adsConfig.cmake
+++ b/adsConfig.cmake
@@ -2,5 +2,7 @@ include(CMakeFindDependencyMacro)
 find_dependency(Qt5Core ${REQUIRED_QT_VERSION} REQUIRED)
 find_dependency(Qt5Gui ${REQUIRED_QT_VERSION} REQUIRED)
 find_dependency(Qt5Widgets ${REQUIRED_QT_VERSION} REQUIRED)
-find_dependency(Qt5X11Extras ${REQUIRED_QT_VERSION} REQUIRED)
+if(UNIX AND NOT APPLE)
+    find_dependency(Qt5X11Extras ${REQUIRED_QT_VERSION} REQUIRED)
+endif()
 include("${CMAKE_CURRENT_LIST_DIR}/adsTargets.cmake")
\ No newline at end of file
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index abe86ba..c2d6e37 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.5)
 project(QtAdvancedDockingSystem LANGUAGES CXX VERSION ${VERSION_SHORT})
 find_package(Qt5 5.5 COMPONENTS Core Gui Widgets REQUIRED)
-if (UNIX)
+if (UNIX AND NOT APPLE)
 	find_package(Qt5 5.5 COMPONENTS X11Extras REQUIRED)
 endif()
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
@@ -48,7 +48,7 @@ set(ads_HEADERS
     IconProvider.h
     DockComponentsFactory.h
 )
-if (UNIX)
+if (UNIX AND NOT APPLE)
     set(ads_SRCS linux/FloatingWidgetTitleBar.cpp ${ads_SRCS})
     set(ads_HEADERS linux/FloatingWidgetTitleBar.h ${ads_HEADERS})
 endif()
diff --git a/src/DockFocusController.cpp b/src/DockFocusController.cpp
index 77e73c1..6f3318a 100644
--- a/src/DockFocusController.cpp
+++ b/src/DockFocusController.cpp
@@ -240,7 +240,11 @@ void CDockFocusController::onApplicationFocusChanged(QWidget* focusedOld, QWidge
 		auto OtherDockWidgetTab = internal::findParent<CDockWidgetTab*>(focusedNow);
 		if (OtherDockWidgetTab && focusedOld)
 		{
-			focusedOld->setFocus();
+			auto OldFocusedDockWidget = internal::findParent<CDockWidget*>(focusedOld);
+			if (OldFocusedDockWidget)
+			{
+				focusedOld->setFocus();
+			}
 			return;
 		}
 	}
diff --git a/src/DockManager.cpp b/src/DockManager.cpp
index 16b2d01..a7b0ddb 100644
--- a/src/DockManager.cpp
+++ b/src/DockManager.cpp
@@ -55,6 +55,7 @@
 #include "DockingStateReader.h"
 #include "DockAreaTitleBar.h"
 #include "DockFocusController.h"
+#include "DockSplitter.h"
 
 #ifdef Q_OS_LINUX
 #include "linux/FloatingWidgetTitleBar.h"
@@ -1093,6 +1094,34 @@ CDockWidget* CDockManager::focusedDockWidget() const
 	}
 }
 
+//===========================================================================
+QList<int> CDockManager::splitterSizes(CDockAreaWidget *ContainedArea) const
+{
+    if (ContainedArea)
+    {
+        auto Splitter = internal::findParent<CDockSplitter*>(ContainedArea);
+        if (Splitter)
+        {
+            return Splitter->sizes();
+        }
+    }
+    return QList<int>();
+}
+
+//===========================================================================
+void CDockManager::setSplitterSizes(CDockAreaWidget *ContainedArea, const QList<int>& sizes)
+{
+    if (!ContainedArea)
+    {
+        return;
+    }
+
+    auto Splitter = internal::findParent<CDockSplitter*>(ContainedArea);
+    if (Splitter && Splitter->count() == sizes.count())
+    {
+        Splitter->setSizes(sizes);
+    }
+}
 
 } // namespace ads
 
diff --git a/src/DockManager.h b/src/DockManager.h
index 8832415..c3924d3 100644
--- a/src/DockManager.h
+++ b/src/DockManager.h
@@ -487,6 +487,25 @@ public:
 	 */
 	CDockWidget* focusedDockWidget() const;
 
+    /**
+     * Returns the sizes of the splitter that contains the dock area.
+     *
+     * If there is no splitter that contains the area, an empty list will be
+     * returned.
+     */
+    QList<int> splitterSizes(CDockAreaWidget *ContainedArea) const;
+
+    /**
+     * Update the sizes of a splitter
+     * Programmatically updates the sizes of a given splitter by calling
+     * QSplitter::setSizes(). The splitter will be the splitter that
+     * contains the supplied dock area widget. If there is not splitter
+     * that contains the dock area, or the sizes supplied does not match
+     * the number of children of the splitter, this method will have no
+     * effect.
+     */
+    void setSplitterSizes(CDockAreaWidget *ContainedArea, const QList<int>& sizes);
+
 public slots:
 	/**
 	 * Opens the perspective with the given name.
diff --git a/src/stylesheets/default.css b/src/stylesheets/default.css
index f5cd680..6ae011a 100644
--- a/src/stylesheets/default.css
+++ b/src/stylesheets/default.css
@@ -5,7 +5,7 @@ ads--CDockContainerWidget {
 	background: palette(dark);
 }
 
-ads--CDockContainerWidget QSplitter::handle {
+ads--CDockContainerWidget ads--CDockSplitter::handle {
 	background: palette(dark);
 }
 
diff --git a/src/stylesheets/default_linux.css b/src/stylesheets/default_linux.css
index 51e52ac..bf7f336 100644
--- a/src/stylesheets/default_linux.css
+++ b/src/stylesheets/default_linux.css
@@ -5,7 +5,7 @@ ads--CDockContainerWidget {
 	background: palette(dark);
 }
 
-ads--CDockContainerWidget QSplitter::handle {
+ads--CDockContainerWidget ads--CDockSplitter::handle {
 	background: palette(dark);
 }
 
diff --git a/src/stylesheets/focus_highlighting_linux.css b/src/stylesheets/focus_highlighting_linux.css
index bea52d0..888092f 100644
--- a/src/stylesheets/focus_highlighting_linux.css
+++ b/src/stylesheets/focus_highlighting_linux.css
@@ -5,7 +5,7 @@ ads--CDockContainerWidget {
         background: palette(dark);
 }
 
-ads--CDockContainerWidget QSplitter::handle {
+ads--CDockContainerWidget ads--CDockSplitter::handle {
         background: palette(dark);
 }
 
@@ -192,3 +192,4 @@ ads--CFloatingDockContainer[isActiveWindow="true"] #floatingTitleMaximizeButton:
     background: rgba(255, 255, 255, 92);
 }
 */
+