diff --git a/Improvements-in-v3.5.0.md b/Improvements-in-v3.5.0.md
index 952a0d4..22000e6 100644
--- a/Improvements-in-v3.5.0.md
+++ b/Improvements-in-v3.5.0.md
@@ -349,6 +349,36 @@ _Released to registered users of the Plus Edition on January 25, 2021._
 * In WindowContainer, calling Children.Remove() no longer throws a NullRefException for a null child.
 * In Zoombox, re-connecting during a remote desktop connection session no longer raises a NullRefException.
 
+## <a id="Plus420"></a>v4.2.0 Plus Edition
+
+_Released to registered users of the Plus Edition on July 19, 2021._
+
+**23 improvements and bug fixes**
+
+* In AvalonDock, the LayoutContent.IsFloating property now raises a PropertyChanged event when a LayoutAnchorable/LayoutDocument starts/ends floating. This allows to add a binding on the IsFloating property.
+* In AvalonDock, floating a LayoutAnchorable no longer shrinks a neighboring LayoutDocument.
+* In AvalonDock, the LayoutItem.CanClose/IsSelected/IsActive/CanTogglePin properties can now be changed dynamically.
+* In AvalonDock, floating a LayoutAnchorable contained in a multi-LayoutAnchorableGroup with specific star sizes no longer resets the sizes of the remaining LayoutItems after the floating.
+* In AvalonDock, moving LayoutDocumentTabItems to reorder them no longer creates a floating window as soon as the mouse leaves the LayoutDocumentTabItem's top and bottom. Instead, a vertical buffer is now added to create moving smoothness.
+* In PropertyGrid, removing a value from an UpDown editor no longer throws an exception.
+* In PropertyGrid, NullRefException are no longer raised while checking for invalid values of PropertyItems.
+* In PropertyGrid, readonly properties using the type converter EnumDisplayNameConverter now display the converted value with the TextBlockEditor.
+* In PropertyGrid, a new Password editor is now available for all properties using a PasswordPropertyText attribute.
+* In all UpDown controls, new properties are now available to set the width/height of the ButtonSpinner.
+* In all UpDown controls, new properties are now available to easily modify the content of the Up/Down arrows (for both enabled and disabled state).
+* In ButtonSpinner, the property ButtonSpinnerLocation is now obsolete; SpinnerLocation should now be used.
+* In ButtonSpinner, the property ShowButtonSpinner is now obsolete; ShowSpinner should now be used.
+* In CheckComboBox/CheckListBox, doing a "Select All" now only raises an ItemSelectionChangedEvent for the unselected items. Similarly, doing a "UnSelect All" now only raises an ItemSelectionChangedEvent for the selected items.
+* In ChildWindow, the default header background now uses Windows' default header background.
+* In StyleableWindow, clicking on the header icon now pops the SystemMenu at the left of the window. Clicking again now closes the SystemMenu.
+* In Themes, using the DataGrid now loads data faster.
+* In DataGrid, unused variables are now removed, resulting in no warnings while compiling.
+* In UI Automation, the PropertyGridTextBoxEditor now shows the TextBox content in the automation tool.
+* In ColorPicker, the popup containing many colors now has a scrollbar when the list of colors is too long.
+* In DateTimePicker, the Culture in the application is now set for the DateTimePicker's Calendar.
+* In CalculatorUpDown, DateTimePicker and TimePicker, new properties are now availables to customize the content of the DropDown button (whether it is enabled or not).
+* All controls from Toolkit (and DataGrid) now support the .NET 5 Framework.
+
 We hope you love this release and decide to support the project by getting a license to Xceed Toolkit Plus for WPF.
 -- Xceed Team