xcb: Fix logic for minimized state

When _NET_WM_STATE_HIDDEN is not contains in the _NET_WM_STATE
window property, the window should not be considered to be minimized

According to
https://specifications.freedesktop.org/wm-spec/1.3/ar01s05.html
_NET_WM_STATE_HIDDEN should be set by the Window Manager to indicate
that a window would not be visible on the screen if its desktop/viewport
were active and its coordinates were within the screen bounds. The
canonical example is that minimized windows should be in the
_NET_WM_STATE_HIDDEN state. Pagers and similar applications should use
_NET_WM_STATE_HIDDEN instead of WM_STATE to decide whether to display a
window in miniature representations of the windows on a desktop.

For mutter/GNOME Shell, without _NET_WM_STATE_HIDDEN, window manager
will not reply XCB_ICCCM_WM_STATE_ICONIC settings in WM_CHANGE_STATE
client message.

Task-number: QTBUG-76147
Task-number: QTBUG-76354
Task-number: QTBUG-68864
Done-With: Liang Qi <liang.qi@qt.io>
Change-Id: Ic9d26d963979b7f0ef4d1cf322c54ef8c40fa004
Reviewed-by: Uli Schlachter <psychon@znc.in>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
(cherry picked from commit 4f370d36ec5caa02f78545ceee5704d94edf0530)

4 files changed, 19 insertions, 3 deletions

diff --git a/src/plugins/platforms/xcb/qxcbatom.cpp b/src/plugins/platforms/xcb/qxcbatom.cpp
index ecb73cb90b..d366564dd6 100644
--- a/src/plugins/platforms/xcb/qxcbatom.cpp
+++ b/src/plugins/platforms/xcb/qxcbatom.cpp
@@ -122,6 +122,7 @@ static const char *xcb_atomnames = {
     "_NET_WM_STATE_MODAL\0"
     "_NET_WM_STATE_STAYS_ON_TOP\0"
     "_NET_WM_STATE_DEMANDS_ATTENTION\0"
+    "_NET_WM_STATE_HIDDEN\0"
 
     "_NET_WM_USER_TIME\0"
     "_NET_WM_USER_TIME_WINDOW\0"
diff --git a/src/plugins/platforms/xcb/qxcbatom.h b/src/plugins/platforms/xcb/qxcbatom.h
index 233d2eadb7..80b5887395 100644
--- a/src/plugins/platforms/xcb/qxcbatom.h
+++ b/src/plugins/platforms/xcb/qxcbatom.h
@@ -123,6 +123,7 @@ public:
         _NET_WM_STATE_MODAL,
         _NET_WM_STATE_STAYS_ON_TOP,
         _NET_WM_STATE_DEMANDS_ATTENTION,
+        _NET_WM_STATE_HIDDEN,
 
         _NET_WM_USER_TIME,
         _NET_WM_USER_TIME_WINDOW,
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 3bfcbf2adb..d7d5bd3958 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -933,6 +933,8 @@ QXcbWindow::NetWmStates QXcbWindow::netWmStates()
             result |= NetWmStateStaysOnTop;
         if (statesEnd != std::find(states, statesEnd, atom(QXcbAtom::_NET_WM_STATE_DEMANDS_ATTENTION)))
             result |= NetWmStateDemandsAttention;
+        if (statesEnd != std::find(states, statesEnd, atom(QXcbAtom::_NET_WM_STATE_HIDDEN)))
+            result |= NetWmStateHidden;
     } else {
         qCDebug(lcQpaXcb, "getting net wm state (%x), empty\n", m_window);
     }
@@ -1104,6 +1106,9 @@ void QXcbWindow::setNetWmStateOnUnmappedWindow()
         states |= NetWmStateBelow;
     }
 
+    if (window()->windowStates() & Qt::WindowMinimized)
+        states |= NetWmStateHidden;
+
     if (window()->windowStates() & Qt::WindowFullScreen)
         states |= NetWmStateFullScreen;
 
@@ -1137,6 +1142,8 @@ void QXcbWindow::setNetWmStateOnUnmappedWindow()
         atoms.push_back(atom(QXcbAtom::_NET_WM_STATE_ABOVE));
     if (states & NetWmStateBelow && !atoms.contains(atom(QXcbAtom::_NET_WM_STATE_BELOW)))
         atoms.push_back(atom(QXcbAtom::_NET_WM_STATE_BELOW));
+    if (states & NetWmStateHidden && !atoms.contains(atom(QXcbAtom::_NET_WM_STATE_HIDDEN)))
+        atoms.push_back(atom(QXcbAtom::_NET_WM_STATE_HIDDEN));
     if (states & NetWmStateFullScreen && !atoms.contains(atom(QXcbAtom::_NET_WM_STATE_FULLSCREEN)))
         atoms.push_back(atom(QXcbAtom::_NET_WM_STATE_FULLSCREEN));
     if (states & NetWmStateMaximizedHorz && !atoms.contains(atom(QXcbAtom::_NET_WM_STATE_MAXIMIZED_HORZ)))
@@ -2236,10 +2243,16 @@ void QXcbWindow::handlePropertyNotifyEvent(const xcb_property_notify_event_t *ev
                                    || (data[0] == XCB_ICCCM_WM_STATE_WITHDRAWN && m_minimized));
             }
         }
-        if (m_minimized)
-            newState = Qt::WindowMinimized;
 
         const NetWmStates states = netWmStates();
+        // _NET_WM_STATE_HIDDEN should be set by the Window Manager to indicate that a window would
+        // not be visible on the screen if its desktop/viewport were active and its coordinates were
+        // within the screen bounds. The canonical example is that minimized windows should be in
+        // the _NET_WM_STATE_HIDDEN state.
+        if (m_minimized && (!connection()->wmSupport()->isSupportedByWM(NetWmStateHidden)
+                            || states.testFlag(NetWmStateHidden)))
+            newState = Qt::WindowMinimized;
+
         if (states & NetWmStateFullScreen)
             newState |= Qt::WindowFullScreen;
         if ((states & NetWmStateMaximizedHorz) && (states & NetWmStateMaximizedVert))
diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index 8258cc2dfa..7f86fc6bb6 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -68,7 +68,8 @@ public:
         NetWmStateMaximizedVert = 0x10,
         NetWmStateModal = 0x20,
         NetWmStateStaysOnTop = 0x40,
-        NetWmStateDemandsAttention = 0x80
+        NetWmStateDemandsAttention = 0x80,
+        NetWmStateHidden = 0x100
     };
 
     Q_DECLARE_FLAGS(NetWmStates, NetWmState)