Document and test resetting properties in a state change.

Task-number: QT-1817

1 files changed, 28 insertions, 1 deletions

diff --git a/src/declarative/util/qdeclarativepropertychanges.cpp b/src/declarative/util/qdeclarativepropertychanges.cpp
index 6c2e256..454fb06 100644
--- a/src/declarative/util/qdeclarativepropertychanges.cpp
+++ b/src/declarative/util/qdeclarativepropertychanges.cpp
@@ -60,7 +60,7 @@ QT_BEGIN_NAMESPACE
 
 /*!
     \qmlclass PropertyChanges QDeclarativePropertyChanges
-  \since 4.7
+    \since 4.7
     \brief The PropertyChanges element describes new property values for a state.
 
     PropertyChanges provides a state change that modifies the properties of an item.
@@ -98,6 +98,33 @@ QT_BEGIN_NAMESPACE
     }
     \endqml
 
+    You can reset a property in a state change by assigning \c undefined. In the following
+    example we reset \c theText's width when we enter state1. This will give the text its
+    natural width (which is the whole string on one line).
+
+    \qml
+    import Qt 4.6
+
+    Rectangle {
+        width: 640
+        height: 480
+        Text {
+            id: theText
+            width: 50
+            wrap: true
+            text: "a text string that is longer than 50 pixels"
+        }
+
+        states: State {
+            name: "state1"
+            PropertyChanges {
+                target: theText
+                width: undefined
+            }
+        }
+    }
+    \endqml
+
     Changes to an Item's parent or anchors should be done using the associated change elements
     (ParentChange and AnchorChanges, respectively) rather than PropertyChanges.