When filling the checker pattern from multiple threads, y_start
needs to be taken into account to determine the shade of the
current pixel.
Example pipeline:
gst-launch-1.0 videotestsrc ! video/x-raw, width=1920, height=1080, format=I420 ! \
queue ! compositor sink_0::xpos=200 ! video/x-raw, format=I420 ! videoconvert ! \
xvimagesink
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/988>
e0a4d3ac4e