Bug with toolbar focus on Mac

Before doing anything we need to make sure that we don't leave anything
in a non-consistent state. When hiding a widget we need to make sure that
no mouse_down events are active, because the mouse_up event will never be
received by a hidden widget or one of its descendants. The solution is
simple, before going through with this we check if there are any
mouse_down events in progress, if so we check if it is related to this
widget or not. If so, we just reset the mouse_down and then we continue.
In X11 and Windows we send a mouse_release event, however we don't do that
here because we were already ignoring that from before. I.e. Carbon did
not send the mouse release event, so we will not send the mouse release
event. There are two ways to interpret this:
1. If we don't send the mouse release event, the widget might get into an
inconsistent state, i.e. it might be waiting for a release event that
will never arrive.
2. If we send the mouse release event, then the widget might decide to
trigger an action that is not supposed to trigger because it is not visible.

Task-number: QTBUG-8604
Reviewed-by: denis

2 files changed, 19 insertions, 5 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 29ae51f..66140ca 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -160,6 +160,7 @@ static inline bool hasBackingStoreSupport()
 
 extern bool qt_sendSpontaneousEvent(QObject*, QEvent*); // qapplication.cpp
 extern QDesktopWidget *qt_desktopWidget; // qapplication.cpp
+extern QPointer<QWidget> qt_button_down; //qapplication_mac.cpp
 
 QWidgetPrivate::QWidgetPrivate(int version)
     : QObjectPrivate(version)
@@ -7535,6 +7536,23 @@ void QWidgetPrivate::hideChildren(bool spontaneous)
         QWidget *widget = qobject_cast<QWidget*>(childList.at(i));
         if (!widget || widget->isWindow() || widget->testAttribute(Qt::WA_WState_Hidden))
             continue;
+#ifdef QT_MAC_USE_COCOA
+        // Before doing anything we need to make sure that we don't leave anything in a non-consistent state.
+        // When hiding a widget we need to make sure that no mouse_down events are active, because
+        // the mouse_up event will never be received by a hidden widget or one of its descendants.
+        // The solution is simple, before going through with this we check if there are any mouse_down events in
+        // progress, if so we check if it is related to this widget or not. If so, we just reset the mouse_down and
+        // then we continue.
+        // In X11 and Windows we send a mouse_release event, however we don't do that here because we were already
+        // ignoring that from before. I.e. Carbon did not send the mouse release event, so we will not send the
+        // mouse release event. There are two ways to interpret this:
+        // 1. If we don't send the mouse release event, the widget might get into an inconsistent state, i.e. it
+        // might be waiting for a release event that will never arrive.
+        // 2. If we send the mouse release event, then the widget might decide to trigger an action that is not
+        // supposed to trigger because it is not visible.
+        if(widget == qt_button_down)
+            qt_button_down = 0;
+#endif // QT_MAC_USE_COCOA
         if (spontaneous)
             widget->setAttribute(Qt::WA_Mapped, false);
         else
diff --git a/src/gui/kernel/qwidget_mac.mm b/src/gui/kernel/qwidget_mac.mm
index c7acf69..5bce17f 100644
--- a/src/gui/kernel/qwidget_mac.mm
+++ b/src/gui/kernel/qwidget_mac.mm
@@ -152,6 +152,7 @@ static bool qt_mac_raise_process = true;
 static OSWindowRef qt_root_win = 0;
 QWidget *mac_mouse_grabber = 0;
 QWidget *mac_keyboard_grabber = 0;
+extern QPointer<QWidget> qt_button_down; //qapplication_mac.cpp
 
 #ifndef QT_MAC_USE_COCOA
 #ifdef QT_NAMESPACE
@@ -866,7 +867,6 @@ OSStatus QWidgetPrivate::qt_window_event(EventHandlerCallRef er, EventRef event,
                                                            & ~Qt::WindowMaximized));
                 QApplication::sendSpontaneousEvent(widget, &e);
             }
-            extern QPointer<QWidget> qt_button_down; //qapplication_mac.cpp
             qt_button_down = 0;
         } else if(ekind == kEventWindowCollapsed) {
             if (!widget->isMinimized()) {
@@ -894,7 +894,6 @@ OSStatus QWidgetPrivate::qt_window_event(EventHandlerCallRef er, EventRef event,
             //we send a hide to be like X11/Windows
             QEvent e(QEvent::Hide);
             QApplication::sendSpontaneousEvent(widget, &e);
-            extern QPointer<QWidget> qt_button_down; //qapplication_mac.cpp
             qt_button_down = 0;
         } else if(ekind == kEventWindowToolbarSwitchMode) {
             macSendToolbarChangeEvent(widget);
@@ -1519,7 +1518,6 @@ OSStatus QWidgetPrivate::qt_widget_event(EventHandlerCallRef er, EventRef event,
             if (widget) {
                 qt_event_request_window_change(widget);
                 if (!HIViewIsVisible(HIViewRef(widget->winId()))) {
-                    extern QPointer<QWidget> qt_button_down; //qapplication_mac.cpp
                     if (widget == qt_button_down)
                         qt_button_down = 0;
                 }
@@ -1528,7 +1526,6 @@ OSStatus QWidgetPrivate::qt_widget_event(EventHandlerCallRef er, EventRef event,
         break; }
     case kEventClassMouse: {
         bool send_to_app = false;
-        extern QPointer<QWidget> qt_button_down; //qapplication_mac.cpp
         if(qt_button_down)
             send_to_app = true;
         if(send_to_app) {
@@ -3405,7 +3402,6 @@ void QWidgetPrivate::hide_sys()
     Q_Q(QWidget);
     if((q->windowType() == Qt::Desktop)) //you can't hide the desktop!
         return;
-
     QMacCocoaAutoReleasePool pool;
     if(q->isWindow()) {
         OSWindowRef window = qt_mac_window_for(q);