From f9e4402ffeef791e66b7b2f2cc332000df7f5cd4 Mon Sep 17 00:00:00 2001
From: Liang Qi <liang.qi@qt.io>
Date: Thu, 7 Apr 2022 11:14:06 +0200
Subject: [PATCH] xcb: recreate xcb window under some conditions
MIME-Version: 1.0
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Some netWmState needs to be set during unmap/hide(), which is too
difficult to follow, and causes m_mapped status out of sync very easily
sometimes, which we had tried in
e946e6895a8517a887ac246905e0769edd766fcc .

Destroy the xcb window and recreate new could make the thing
much easier. This practice is also used in other platforms, such
as cocoa plugin.

In Qt 4, the platform window was destoryed and re-created in this
situation on all platforms, which was not ported into Qt5.

See also the code between setWinId(0) and createWinId() in
QWidgetPrivate::setParent_sys() in qwidget_x11.cpp/qwidget_win.cpp/
qwidget_mac.mm.

Fixes: QTBUG-69515
Fixes: QTBUG-73485
Fixes: QTBUG-81341
Pick-to: 6.3 6.2 5.15
Change-Id: If55c57a198bc785719b61b8748dabd8281c9639d
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
---
 src/plugins/platforms/xcb/qxcbwindow.cpp | 14 ++++++++++++++
 src/plugins/platforms/xcb/qxcbwindow.h   |  9 +++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 25a4bd5fa5f..1d8450a7553 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -92,6 +92,8 @@ enum {
 
 QT_BEGIN_NAMESPACE
 
+Q_LOGGING_CATEGORY(lcQpaWindow, "qt.qpa.window");
+
 Q_DECLARE_TYPEINFO(xcb_rectangle_t, Q_PRIMITIVE_TYPE);
 
 #undef FocusIn
@@ -539,6 +541,7 @@ void QXcbWindow::destroy()
     }
 
     m_mapped = false;
+    m_recreationReasons = RecreationNotNeeded;
 
     if (m_pendingSyncRequest)
         m_pendingSyncRequest->invalidate();
@@ -673,6 +676,11 @@ void QXcbWindow::setVisible(bool visible)
 void QXcbWindow::show()
 {
     if (window()->isTopLevel()) {
+        if (m_recreationReasons != RecreationNotNeeded) {
+            qCDebug(lcQpaWindow) << "QXcbWindow: need to recreate window" << window() << m_recreationReasons;
+            create();
+            m_recreationReasons = RecreationNotNeeded;
+        }
 
         // update WM_NORMAL_HINTS
         propagateSizeHints();
@@ -888,6 +896,12 @@ void QXcbWindow::setWindowFlags(Qt::WindowFlags flags)
     if (type == Qt::Popup)
         flags |= Qt::X11BypassWindowManagerHint;
 
+    Qt::WindowFlags oldflags = window()->flags();
+    if ((oldflags & Qt::WindowStaysOnTopHint) != (flags & Qt::WindowStaysOnTopHint))
+        m_recreationReasons |= WindowStaysOnTopHintChanged;
+    if ((oldflags & Qt::WindowStaysOnBottomHint) != (flags & Qt::WindowStaysOnBottomHint))
+        m_recreationReasons |= WindowStaysOnBottomHintChanged;
+
     const quint32 mask = XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK;
     const quint32 values[] = {
          // XCB_CW_OVERRIDE_REDIRECT
diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index 2c65296d90a..74d953df966 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -74,6 +74,13 @@ public:
 
     Q_DECLARE_FLAGS(NetWmStates, NetWmState)
 
+    enum RecreationReason {
+        RecreationNotNeeded = 0,
+        WindowStaysOnTopHintChanged = 0x1,
+        WindowStaysOnBottomHintChanged = 0x2
+    };
+    Q_DECLARE_FLAGS(RecreationReasons, RecreationReason)
+
     QXcbWindow(QWindow *window);
     ~QXcbWindow();
 
@@ -280,6 +287,8 @@ protected:
     int m_swapInterval = -1;
 
     qreal m_sizeHintsScaleFactor = 1.0;
+
+    RecreationReasons m_recreationReasons = RecreationNotNeeded;
 };
 
 class QXcbForeignWindow : public QXcbWindow