Comment 1 for bug 1539268

The surfacelesscontext created uses a default attribute list which may not match the actual attribute list used to create the egl context associated with the nested display.

This is problematic for qtmir - as it creates a temporary context in an effort to query the underlying eglconfig used for the display and inform Qt about R/G/B/A/Depth/stencil sizes.

If the surfaceless context happens to choose a config that has no alpha, qtmir will inform Qt that there's no alpha (when there actually is) and rendering artifacts can occur.