Make sure QWidget::setStyle() relayouts its children.

Changing a style on a widget should invalidate the widget's layout,
since the layouts spacings and margins may depend on the style.

One optimization could be to check to see if the spacing and margins
have changed due to the style change, but the old style is not available
in changeEvent, so we'll keep it simple for now.

RevBy: paul
Task: 256986

2 files changed, 3 insertions, 2 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 60a6b7a..f705761 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -7990,10 +7990,12 @@ void QWidget::changeEvent(QEvent * event)
 
     case QEvent::FontChange:
     case QEvent::StyleChange: {
+        Q_D(QWidget);
         update();
         updateGeometry();
+        if (d->layout)
+            d->layout->invalidate();
 #ifdef Q_WS_QWS
-        Q_D(QWidget);
         if (isWindow())
             d->data.fstrut_dirty = true;
 #endif
diff --git a/tests/auto/qboxlayout/tst_qboxlayout.cpp b/tests/auto/qboxlayout/tst_qboxlayout.cpp
index 642bc77..5803985 100644
--- a/tests/auto/qboxlayout/tst_qboxlayout.cpp
+++ b/tests/auto/qboxlayout/tst_qboxlayout.cpp
@@ -240,7 +240,6 @@ void tst_QBoxLayout::setStyleShouldChangeSpacing()
     window->setStyle(style2);
     QTest::qWait(100);
     spacing = pb2->geometry().left() - pb1->geometry().right() - 1;
-    QEXPECT_FAIL("", "Fix for next minor release", Continue);
     QCOMPARE(spacing, 10);
 
     delete window;