Copy-paste didn't work for application on non-first screen in multiscreen setup.

We need to subscribe to xfixes selection notify events on all
available screens.

Also implemented delayed subscription to xfixes events since we don't
really need clipboard change notifications unless the application
explicitely asked for by (i.e. created a qclipboard object).

Task-number: 255609
Reviewed-by: Bradley T. Hughes
(cherry picked from commit 8a745d2a1048ba922232530d36c2fd01d4c92159)

2 files changed, 14 insertions, 8 deletions

diff --git a/src/gui/kernel/qapplication_x11.cpp b/src/gui/kernel/qapplication_x11.cpp
index 705e9acefe..0bd7c4d598 100644
--- a/src/gui/kernel/qapplication_x11.cpp
+++ b/src/gui/kernel/qapplication_x11.cpp
@@ -2057,14 +2057,6 @@ void qt_init(QApplicationPrivate *priv, int,
                 X11->xfixes_major = major;
             }
         }
-        if (X11->use_xfixes && X11->ptrXFixesSelectSelectionInput) {
-            const unsigned long eventMask =
-                XFixesSetSelectionOwnerNotifyMask | XFixesSelectionWindowDestroyNotifyMask | XFixesSelectionClientCloseNotifyMask;
-            X11->ptrXFixesSelectSelectionInput(X11->display, QX11Info::appRootWindow(0),
-                                               XA_PRIMARY, eventMask);
-            X11->ptrXFixesSelectSelectionInput(X11->display, QX11Info::appRootWindow(0),
-                                               ATOM(CLIPBOARD), eventMask);
-        }
 #endif // QT_NO_XFIXES
 
 #ifndef QT_NO_XCURSOR
diff --git a/src/gui/kernel/qclipboard_x11.cpp b/src/gui/kernel/qclipboard_x11.cpp
index fe562a3327..98c730a4c6 100644
--- a/src/gui/kernel/qclipboard_x11.cpp
+++ b/src/gui/kernel/qclipboard_x11.cpp
@@ -428,6 +428,20 @@ QClipboard::QClipboard(QObject *parent)
     // XFixesSelectionNotify events when someone changes the
     // clipboard.
     (void)QApplication::desktop();
+
+#ifndef QT_NO_XFIXES
+    if (X11->use_xfixes && X11->ptrXFixesSelectSelectionInput) {
+        const unsigned long eventMask =
+            XFixesSetSelectionOwnerNotifyMask | XFixesSelectionWindowDestroyNotifyMask | XFixesSelectionClientCloseNotifyMask;
+        for (int i = 0; i < X11->screenCount; ++i) {
+            X11->ptrXFixesSelectSelectionInput(X11->display, QX11Info::appRootWindow(i),
+                                               XA_PRIMARY, eventMask);
+            X11->ptrXFixesSelectSelectionInput(X11->display, QX11Info::appRootWindow(i),
+                                               ATOM(CLIPBOARD), eventMask);
+        }
+    }
+#endif // QT_NO_XFIXES
+
     if (X11->time == CurrentTime) {
         // send a dummy event to myself to get the timestamp from X11.
         qt_init_timestamp_data data;