Ensure that child windows are visible again when showing their parent

When a window is closed, then it will cause the child windows to be
closed as well as a result. Therefore in order to ensure that they are
shown again as a result, we need to remove the WA_WState_ExplicitShowHide
attribute if the widget was not already hidden before. This enables us to
test for this attribute when calling showChildren(), so that if the
window has a windowHandle then we can make sure that this widget is shown
again.

Fixes: QTBUG-73021
Change-Id: I1186242b889899dfcd38d782a67567348e2055ee
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 10 insertions, 2 deletions

diff --git a/src/widgets/kernel/qwidgetwindow.cpp b/src/widgets/kernel/qwidgetwindow.cpp
index aad505ed29..878e484ab8 100644
--- a/src/widgets/kernel/qwidgetwindow.cpp
+++ b/src/widgets/kernel/qwidgetwindow.cpp
@@ -72,10 +72,18 @@ public:
     void setVisible(bool visible) override
     {
         Q_Q(QWidgetWindow);
-        if (QWidget *widget = q->widget())
+        if (QWidget *widget = q->widget()) {
+            // Check if the widget was already hidden, as this indicates it was done
+            // explicitly and not because the parent window in this case made it hidden.
+            // In which case do not automatically show the widget when the parent
+            // window is shown.
+            const bool wasHidden = widget->testAttribute(Qt::WA_WState_Hidden);
             QWidgetPrivate::get(widget)->setVisible(visible);
-        else
+            if (!wasHidden)
+                widget->setAttribute(Qt::WA_WState_ExplicitShowHide, false);
+        } else {
             QWindowPrivate::setVisible(visible);
+        }
     }
 
     QWindow *eventReceiver() override {