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-rw-r--r--src/openglwidgets/qopenglwidget.cpp13
1 files changed, 13 insertions, 0 deletions
diff --git a/src/openglwidgets/qopenglwidget.cpp b/src/openglwidgets/qopenglwidget.cpp
index a596416471..2ae1a7f215 100644
--- a/src/openglwidgets/qopenglwidget.cpp
+++ b/src/openglwidgets/qopenglwidget.cpp
@@ -401,6 +401,19 @@ QT_BEGIN_NAMESPACE
each frame. To restore the preserved behavior, call setUpdateBehavior() with
\c PartialUpdate.
+ \note Displaying a QOpenGLWidget requires an alpha channel in the associated
+ top-level window's backing store due to the way composition with other
+ QWidget-based content works. If there is no alpha channel, the content
+ rendered by the QOpenGLWidget will not be visible. This can become
+ particularly relevant on Linux/X11 in remote display setups (such as, with
+ Xvnc), when using a color depth lower than 24. For example, a color depth of
+ 16 will typically map to using a backing store image with the format
+ QImage::Format_RGB16 (RGB565), leaving no room for an alpha
+ channel. Therefore, if experiencing problems with getting the contents of a
+ QOpenGLWidget composited correctly with other the widgets in the window, make
+ sure the server (such as, vncserver) is configured with a 24 or 32 bit depth
+ instead of 16.
+
\section1 Alternatives
Adding a QOpenGLWidget into a window turns on OpenGL-based