Index: qopenglwidget.cpp
===================================================================
--- qopenglwidget.cpp	(revision 6869)
+++ qopenglwidget.cpp	(working copy)
@@ -697,7 +697,11 @@
     QOpenGLFramebufferObjectFormat format;
     format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
     format.setSamples(samples);
-
+    // Check if GL context supports more than 8 bit color depth:
+    if ((samples <= 1) && (context->format().redBufferSize() > 8)) {
+      // we need an internal texture format which can store the higher bit depth:
+      format.setInternalTextureFormat(GL_RGB10_A2);
+    }
     const QSize deviceSize = q->size() * q->devicePixelRatioF();
     fbo = new QOpenGLFramebufferObject(deviceSize, format);
     if (samples > 0)