diff -r ef0373b55136 -r 758a864f9613 src/gui/graphicsview/qgridlayoutengine_p.h
--- a/src/gui/graphicsview/qgridlayoutengine_p.h	Fri Sep 17 08:34:18 2010 +0300
+++ b/src/gui/graphicsview/qgridlayoutengine_p.h	Mon Oct 04 01:19:32 2010 +0300
@@ -91,6 +91,14 @@
     Bottom
 };
 
+enum {
+    NoConstraint,
+    HorizontalConstraint,
+    VerticalConstraint,
+    UnknownConstraint,      // need to update cache
+    UnfeasibleConstraint    // not feasible, it be has some items with Vertical and others with Horizontal constraints
+};
+
 template <typename T>
 class QLayoutParameter
 {
@@ -270,6 +278,10 @@
     inline void setAlignment(Qt::Alignment alignment) { q_alignment = alignment; }
 
     QSizePolicy::Policy sizePolicy(Qt::Orientation orientation) const;
+
+    bool hasDynamicConstraint() const;
+    Qt::Orientation dynamicConstraintOrientation() const;
+
     QSizePolicy::ControlTypes controlTypes(LayoutSide side) const;
     QSizeF sizeHint(Qt::SizeHint which, const QSizeF &constraint = QSizeF()) const;
     QGridLayoutBox box(Qt::Orientation orientation, qreal constraint = -1.0) const;
@@ -280,7 +292,7 @@
     void setGeometry(const QRectF &rect);
     void transpose();
     void insertOrRemoveRows(int row, int delta, Qt::Orientation orientation = Qt::Vertical);
-    QSizeF effectiveMaxSize() const;
+    QSizeF effectiveMaxSize(const QSizeF &constraint) const;
 
 #ifdef QT_DEBUG
     void dump(int indent = 0) const;
@@ -372,6 +384,14 @@
                     int column, int rowSpan, int columnSpan) const;
     QSizeF sizeHint(const QLayoutStyleInfo &styleInfo, Qt::SizeHint which,
                     const QSizeF &constraint) const;
+
+    // heightForWidth / widthForHeight support
+    QSizeF dynamicallyConstrainedSizeHint(Qt::SizeHint which, const QSizeF &constraint) const;
+    bool ensureDynamicConstraint() const;
+    bool hasDynamicConstraint() const;
+    Qt::Orientation constraintOrientation() const;
+
+
     QSizePolicy::ControlTypes controlTypes(LayoutSide side) const;
     void transpose();
     void setVisualDirection(Qt::LayoutDirection direction);
@@ -405,6 +425,7 @@
     // Lazily computed from the above user input
     mutable int q_cachedEffectiveFirstRows[NOrientations];
     mutable int q_cachedEffectiveLastRows[NOrientations];
+    mutable quint8 q_cachedConstraintOrientation : 2;
 
     // Layout item input
     mutable QLayoutStyleInfo q_cachedDataForStyleInfo;