KWin: Show Qubes VM name as suffix

show_vm.diff

diff --git a/atoms.cpp b/atoms.cpp
index 55a8aa3..f5432a4 100644
--- a/atoms.cpp
+++ b/atoms.cpp
@@ -59,6 +59,7 @@ Atoms::Atoms()
     , kwin_dbus_service(QByteArrayLiteral("_ORG_KDE_KWIN_DBUS_SERVICE"))
     , utf8_string(QByteArrayLiteral("UTF8_STRING"))
     , wl_surface_id(QByteArrayLiteral("WL_SURFACE_ID"))
+    , qubes_vm_name(QByteArrayLiteral("_QUBES_VMNAME"))
     , m_dtSmWindowInfo(QByteArrayLiteral("_DT_SM_WINDOW_INFO"))
     , m_motifSupport(QByteArrayLiteral("_MOTIF_WM_INFO"))
     , m_helpersRetrieved(false)
diff --git a/atoms.h b/atoms.h
index f265cee..2dffb83 100644
--- a/atoms.h
+++ b/atoms.h
@@ -68,6 +68,7 @@ public:
     Xcb::Atom kwin_dbus_service;
     Xcb::Atom utf8_string;
     Xcb::Atom wl_surface_id;
+    Xcb::Atom qubes_vm_name;
 
     /**
      * @internal
diff --git a/client.cpp b/client.cpp
index cb8dbf1..8d0abbc 100644
--- a/client.cpp
+++ b/client.cpp
@@ -1479,6 +1479,16 @@ void Client::setCaption(const QString& _s, bool force)
     }
     QString shortcut_suffix = !shortcut().isEmpty() ? (QLatin1String(" {") + shortcut().toString() + QLatin1Char('}')) : QString();
     cap_suffix = machine_suffix + shortcut_suffix;
+
+    // Qubes: Append the VM name if this isn't a dom0 window
+    QString vm = QString::fromUtf8(Xcb::StringProperty(m_client, atoms->qubes_vm_name));
+    if (!vm.isEmpty()) {
+        if (!cap_suffix.isEmpty()) {
+            cap_suffix += QLatin1String(" ");
+        }
+        cap_suffix += vm;
+    }
+
     auto fetchNameInternalPredicate = [this](const Client *cl) {
         return (!cl->isSpecialWindow() || cl->isToolbar()) &&
                 cl != this && cl->caption() == caption();