Always report focusObjectChanged on QWidget::clearFocus()

The focusObject() of a QWidgetWindow is based on the focusWidget() of the
top level widget of the window, which is resolved through the focus_child
chain of the widget. This is not the same thing as the focusWidget of the
application. The hasFocus() function of a QWidget queries the latter, so
we can't put the focusObjectChanged signal inside hasFocus() when we
unconditionally clear the focus_child chain (and hence the focusObject)
earlier in the function.

Change-Id: Iae39da5d6031d22b21e9dc9f18e5fe6e6fd11a5c
Reviewed-by: Jan Arve Sæther <jan-arve.saether@theqtcompany.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index e7d33d3bd8..5529f8f72c 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -6545,10 +6545,15 @@ void QWidget::clearFocus()
 
     QWidget *w = this;
     while (w) {
+        // Just like setFocus(), we update (clear) the focus_child of our parents
         if (w->d_func()->focus_child == this)
             w->d_func()->focus_child = 0;
         w = w->parentWidget();
     }
+    // Since focus_child is the basis for the top level QWidgetWindow's focusObject()
+    // we need to report this change to the rest of Qt, but we match setFocus() and
+    // do it at the end of the function.
+
 #ifndef QT_NO_GRAPHICSVIEW
     QWExtra *topData = d_func()->extra;
     if (topData && topData->proxyWidget)
@@ -6569,11 +6574,15 @@ void QWidget::clearFocus()
             QAccessible::updateAccessibility(&event);
 #endif
         }
+    }
 
-        if (QTLWExtra *extra = window()->d_func()->maybeTopData()) {
-            if (extra->window)
-                emit extra->window->focusObjectChanged(extra->window->focusObject());
-        }
+    // Since we've unconditionally cleared the focus_child of our parents, we need
+    // to report this to the rest of Qt. Note that the focus_child is not the same
+    // thing as the application's focusWidget, which is why this piece of code is
+    // not inside the hasFocus() block above.
+    if (QTLWExtra *extra = window()->d_func()->maybeTopData()) {
+        if (extra->window)
+            emit extra->window->focusObjectChanged(extra->window->focusObject());
     }
 }