macOS: Don't reset focus window to top level window when becoming key

The NSWindow becomes the "key window" when it's the window that currently
receives keyboard events. This happens when switching activation between
windows of the same app, or when the app is made active, restoring the
key window status.

Since the keyWindow property only applies to top level windows we were
skipping child windows when processing the event callback, but we then
proceeded to pass the top level window() to handleFocusWindowChanged,
instead of the QWindow of the key window's first responder (the view
that receives key input sent to the top level key window).

To fix this, we let each platform window send its own focus change
event, if it's the first responder, instead of relying on the top
level window to send it on behalf of possible child windows. This
decoupling ensures that we also send focus changes when we're not
part of a view hierarchy Qt controls.

Task-number: QTBUG-119287
Fixes: QTBUG-119054
Pick-to: 6.7 6.6 6.5
Change-Id: Iac06fe800291e243432335169c52db7685e173df
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 18 insertions, 9 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 0533a6e1e9..e1714b104e 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -1246,19 +1246,21 @@ void QCocoaWindow::windowDidEndLiveResize()
 
 void QCocoaWindow::windowDidBecomeKey()
 {
-    if (!isContentView())
-        return;
-
     if (isForeignWindow())
         return;
 
-    QNSView *firstResponderView = qt_objc_cast<QNSView *>(m_view.window.firstResponder);
-    if (!firstResponderView)
+    // The NSWindow we're part of become key. Check if we're the first
+    // responder, and if so, deliver focus window change to our window.
+    if (m_view.window.firstResponder != m_view)
         return;
 
-    const QCocoaWindow *focusCocoaWindow = firstResponderView.platformWindow;
-    if (focusCocoaWindow->windowIsPopupType())
+    qCDebug(lcQpaWindow) << m_view.window << "became key window."
+        << "Updating focus window to" << this;
+
+    if (windowIsPopupType()) {
+        qCDebug(lcQpaWindow) << "Window is popup. Skipping focus window change.";
         return;
+    }
 
     // See also [QNSView becomeFirstResponder]
     QWindowSystemInterface::handleFocusWindowChanged<QWindowSystemInterface::SynchronousDelivery>(
@@ -1267,12 +1269,17 @@ void QCocoaWindow::windowDidBecomeKey()
 
 void QCocoaWindow::windowDidResignKey()
 {
-    if (!isContentView())
+    if (isForeignWindow())
         return;
 
-    if (isForeignWindow())
+    // The NSWindow we're part of lost key. Check if we're the first
+    // responder, and if so, deliver window deactivation to our window.
+    if (m_view.window.firstResponder != m_view)
         return;
 
+    qCDebug(lcQpaWindow) << m_view.window << "resigned key window."
+        << "Clearing focus window" << this;
+
     // Make sure popups are closed before we deliver activation changes, which are
     // otherwise ignored by QApplication.
     closeAllPopups();
@@ -1283,6 +1290,8 @@ void QCocoaWindow::windowDidResignKey()
     NSWindow *newKeyWindow = [NSApp keyWindow];
     if (newKeyWindow && newKeyWindow != m_view.window
         && [newKeyWindow conformsToProtocol:@protocol(QNSWindowProtocol)]) {
+        qCDebug(lcQpaWindow) << "New key window" << newKeyWindow
+            << "is Qt window. Deferring focus window change.";
         return;
     }