3 files changed, 49 insertions, 15 deletions
diff --git a/src/widgets/kernel/qboxlayout.cpp b/src/widgets/kernel/qboxlayout.cpp
index b01227b8d5..5eaed16694 100644
--- a/src/widgets/kernel/qboxlayout.cpp
+++ b/src/widgets/kernel/qboxlayout.cpp
@@ -547,7 +547,11 @@ QLayoutItem* QBoxLayoutPrivate::replaceAt(int index, QLayoutItem *item)
     Constructs a new QBoxLayout with direction \a dir and parent widget \a
     parent.
 
-    \sa direction()
+    The layout is set directly as the top-level layout for \a parent.
+    There can be only one top-level layout for a widget. It is returned
+    by QWidget::layout().
+
+    \sa direction(), QWidget::setLayout()
 */
 QBoxLayout::QBoxLayout(Direction dir, QWidget *parent)
     : QLayout(*new QBoxLayoutPrivate, nullptr, parent)
@@ -1231,11 +1235,16 @@ QBoxLayout::Direction QBoxLayout::direction() const
     \snippet layouts/layouts.cpp 4
     \snippet layouts/layouts.cpp 5
 
-    First, we create the widgets we want in the layout. Then, we
-    create the QHBoxLayout object and add the widgets into the
-    layout. Finally, we call QWidget::setLayout() to install the
-    QHBoxLayout object onto the widget. At that point, the widgets in
-    the layout are reparented to have \c window as their parent.
+    First, we create the widgets we want to add to the layout. Then,
+    we create the QHBoxLayout object, setting \c window as parent by
+    passing it in the constructor; next we add the widgets to the
+    layout. \c window will be the parent of the widgets that are
+    added to the layout.
+
+    If you don't pass parent \c window in the constrcutor, you can
+    at a later point use QWidget::setLayout() to install the QHBoxLayout
+    object onto \c window. At that point, the widgets in the layout are
+    reparented to have \c window as their parent.
 
     \image qhboxlayout-with-5-children.png Horizontal box layout with five child widgets
 
@@ -1244,8 +1253,13 @@ QBoxLayout::Direction QBoxLayout::direction() const
 
 
 /*!
-    Constructs a new top-level horizontal box with
-    parent \a parent.
+    Constructs a new top-level horizontal box with parent \a parent.
+
+    The layout is set directly as the top-level layout for \a parent.
+    There can be only one top-level layout for a widget. It is returned
+    by QWidget::layout().
+
+    \sa QWidget::setLayout()
 */
 QHBoxLayout::QHBoxLayout(QWidget *parent)
     : QBoxLayout(LeftToRight, parent)
@@ -1294,11 +1308,16 @@ QHBoxLayout::~QHBoxLayout()
     \snippet layouts/layouts.cpp 10
     \snippet layouts/layouts.cpp 11
 
-    First, we create the widgets we want in the layout. Then, we
-    create the QVBoxLayout object and add the widgets into the
-    layout. Finally, we call QWidget::setLayout() to install the
-    QVBoxLayout object onto the widget. At that point, the widgets in
-    the layout are reparented to have \c window as their parent.
+    First, we create the widgets we want to add to the layout. Then,
+    we create the QVBoxLayout object, setting \c window as parent by
+    passing it in the constructor; next we add the widgets to the
+    layout. \c window will be the parent of the widgets that are
+    added to the layout.
+
+    If you don't pass parent \c window in the constrcutor, you can
+    at a later point use QWidget::setLayout() to install the QVBoxLayout
+    object onto \c window. At that point, the widgets in the layout are
+    reparented to have \c window as their parent.
 
     \image qvboxlayout-with-5-children.png Horizontal box layout with five child widgets
 
@@ -1306,8 +1325,13 @@ QHBoxLayout::~QHBoxLayout()
 */
 
 /*!
-    Constructs a new top-level vertical box with
-    parent \a parent.
+    Constructs a new top-level vertical box with parent \a parent.
+
+    The layout is set directly as the top-level layout for \a parent.
+    There can be only one top-level layout for a widget. It is returned
+    by QWidget::layout().
+
+    \sa QWidget::setLayout()
 */
 QVBoxLayout::QVBoxLayout(QWidget *parent)
     : QBoxLayout(TopToBottom, parent)
diff --git a/src/widgets/kernel/qformlayout.cpp b/src/widgets/kernel/qformlayout.cpp
index ec1e5e4156..8c3d3448ca 100644
--- a/src/widgets/kernel/qformlayout.cpp
+++ b/src/widgets/kernel/qformlayout.cpp
@@ -1189,6 +1189,10 @@ QLayoutItem* QFormLayoutPrivate::replaceAt(int index, QLayoutItem *newitem)
 /*!
     Constructs a new form layout with the given \a parent widget.
 
+    The layout is set directly as the top-level layout for \a parent.
+    There can be only one top-level layout for a widget. It is returned
+    by QWidget::layout().
+
     \sa QWidget::setLayout()
 */
 QFormLayout::QFormLayout(QWidget *parent)
diff --git a/src/widgets/kernel/qgridlayout.cpp b/src/widgets/kernel/qgridlayout.cpp
index 339677378f..3a1d89573c 100644
--- a/src/widgets/kernel/qgridlayout.cpp
+++ b/src/widgets/kernel/qgridlayout.cpp
@@ -1072,6 +1072,12 @@ QRect QGridLayoutPrivate::cellRect(int row, int col) const
     Constructs a new QGridLayout with parent widget, \a parent.  The
     layout has one row and one column initially, and will expand when
     new items are inserted.
+
+    The layout is set directly as the top-level layout for \a parent.
+    There can be only one top-level layout for a widget. It is returned
+    by QWidget::layout().
+
+    \sa QWidget::setLayout()
 */
 QGridLayout::QGridLayout(QWidget *parent)
     : QLayout(*new QGridLayoutPrivate, nullptr, parent)