diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -498,6 +498,7 @@
 )
 
 if(KWIN_BUILD_TABBOX)
+    include_directories(${Qt5Gui_PRIVATE_INCLUDE_DIRS})
     set(
         kwin_KDEINIT_SRCS ${kwin_KDEINIT_SRCS}
         tabbox/tabbox.cpp
diff --git a/tabbox/tabboxhandler.cpp b/tabbox/tabboxhandler.cpp
--- a/tabbox/tabboxhandler.cpp
+++ b/tabbox/tabboxhandler.cpp
@@ -42,6 +42,7 @@
 #include <QQuickItem>
 #include <QQuickWindow>
 #include <X11/Xlib.h>
+#include <qpa/qwindowsysteminterface.h>
 // KDE
 #include <KLocalizedString>
 #include <KProcess>
@@ -344,6 +345,8 @@
     if (QWindow *w = window()) {
         wheelAngleDelta = 0;
         w->installEventFilter(q);
+        // pretend to activate the window to enable accessibility notifications
+        QWindowSystemInterface::handleWindowActivated(w, Qt::TabFocusReason);
     }
 #endif
 }