Graphics View: OpenGL format handling problems

[maxGimeno]

Issue Details

When the first attempt to generate a 4.3 GL context fails, the qglviewer should create a 2.1 GLES context, but it is not used then. The first created context is still used instead, which makes the option '--old' useless and keeps osx users from drawing edges and points with shaders that manage edge/point size.

[lrineau]

@maxGimeno What do you plan to do to address this issue?

[maxGimeno]

I have to experiment to find a way to change an ongoing context at runtime. One of my ideas was to use a setting file to store the right context and display an error mesasge when the creation failed, asking to restart the application.