1 files changed, 12 insertions, 2 deletions
diff --git a/src/plugins/platforms/qnx/qqnxwindow.cpp b/src/plugins/platforms/qnx/qqnxwindow.cpp
index f4cbb0e9db..7a1ffb98b8 100644
--- a/src/plugins/platforms/qnx/qqnxwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxwindow.cpp
@@ -117,9 +117,13 @@ QQnxWindow::QQnxWindow(QWindow *window, screen_context_t context)
     if (result != 0)
         qFatal("QQnxWindow: failed to set window alpha mode, errno=%d", errno);
 
-    // Make the window opaque
+    // Blend the window with Source Over Porter-Duff behavior onto whatever's
+    // behind it.
+    //
+    // If the desired use-case is opaque, the Widget painting framework will
+    // already fill in the alpha channel with full opacity.
     errno = 0;
-    val = SCREEN_TRANSPARENCY_NONE;
+    val = SCREEN_TRANSPARENCY_SOURCE_OVER;
     result = screen_set_window_property_iv(m_window, SCREEN_PROPERTY_TRANSPARENCY, &val);
     if (result != 0)
         qFatal("QQnxWindow: failed to set window transparency, errno=%d", errno);
@@ -370,6 +374,12 @@ void QQnxWindow::setBufferSize(const QSize &size)
             qWarning() << "QQnxWindow: Buffer size was" << size;
             qFatal("QQnxWindow: failed to create window buffers, errno=%d", errno);
 
+        // If the child window has been configured for transparency, lazily create
+        // a full-screen buffer to back the root window.
+        if (window()->requestedFormat().hasAlpha()) {
+            m_screen->rootWindow()->makeTranslucent();
+        }
+
         // check if there are any buffers available
         int bufferCount = 0;
         result = screen_get_window_property_iv(m_window, SCREEN_PROPERTY_RENDER_BUFFER_COUNT, &bufferCount);