xwl: Do not refresh the x11 Clipboard while fetching

At the moment there was a race condition when putting something into the
keyboard from XWayland apps. The clipboard manager would announce a new
thing before we'd submitted it all resulting in a broken state.

This change detects when it's fetching and will only refresh the source
after everything has been sent.

BUG: 424754
CCBUG: 412350
(cherry picked from commit d335070b80)

xwl/clipboard.cpp

@@ -66,6 +66,10 @@ Clipboard::Clipboard(xcb_atom_t atom, QObject *parent)
 
 void Clipboard::wlSelectionChanged(KWaylandServer::AbstractDataSource *dsi)
 {
+    if (m_waitingForTargets) {
+        return;
+    }
+
     if (dsi && !ownsSelection(dsi)) {
         // Wayland native client provides new selection
         if (!m_checkConnection) {
@@ -88,6 +92,10 @@ bool Clipboard::ownsSelection(KWaylandServer::AbstractDataSource *dsi) const
 
 void Clipboard::checkWlSource()
 {
+    if (m_waitingForTargets) {
+        return;
+    }
+
     auto dsi = waylandServer()->seat()->selection();
     auto removeSource = [this] {
         if (wlSource()) {
@@ -145,6 +153,7 @@ void Clipboard::doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event)
 
     if (X11Source *source = x11Source()) {
         source->getTargets();
+        m_waitingForTargets = true;
     } else {
         qCWarning(KWIN_XWL) << "Could not create a source from" << event << Qt::hex << (event ? event->owner : -1);
     }
@@ -152,6 +161,7 @@ void Clipboard::doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event)
 
 void Clipboard::x11OffersChanged(const QStringList &added, const QStringList &removed)
 {
+    m_waitingForTargets = false;
     X11Source *source = x11Source();
     if (!source) {
         qCWarning(KWIN_XWL) << "offers changed when not having an X11Source!?";

xwl/clipboard.h

@@ -53,6 +53,7 @@ private:
     QMetaObject::Connection m_checkConnection;
 
     Q_DISABLE_COPY(Clipboard)
+    bool m_waitingForTargets = false;
 };
 
 } // namespace Xwl