[Interest] Stacking QOpenGLWidgets

[Allan Sandfeld Jensen]

On Wednesday 27 January 2016, Uwe Rathmann wrote:
> Hi all,
> 
> I'm trying to create an application with several QOpenGLWidgets ( no
> regular QWidgets involved ), where some of them are on top of others.
> 
> My first results are promising, but I couldn't find out how to enable a
> transparent background for the widgets on top. I would like to have a
> similar effect as with setAutoFillBackground( false ) - seeing pixels
> from the widget below.
> 
> But I also couldn't get setAutoFillBackground(true) working and had to
> fill widgets myself in paintGL(). As it is explicitly mentioned in
> the docs ( http://doc.qt.io/qt-5/qopenglwidget.html ) I guess it
> is something wrong on my side.
> 
> When having a regular widget on top of a QOpenGLWidget everything works
> like expected, but with QOpenGLWidget the background is always black.
> 
> Has someone ever tried this or knows if it is possible to set up
> QOpenGLWidget not drawing a background at all ?
> 
Yes it is somewhat possible. We configured it to work in QtWebEngineView, look 
in render_widget_host_view_qt_delegate.cpp 

According to the comment there, it apparently required setting 
WA_AlwaysStackOnTop.

`Allan