Merge branch '1626-qopenglwidget' into 'develop'

BUG: migrate to QOpenGLWidget

Closes #1796 and #1626

See merge request !655
2 jobs for nightly in 5 minutes and 37 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Precheck
passed #17629
fast-build

00:05:37

 
  External
passed cdash:ubuntu-18.04-fast