Add offscreen-canvas support for the jupyterlite-xeus case

docs/conf.py

@@ -4,6 +4,11 @@
 jupyterlite_dir = "."
 jupyterlite_silence = False
 
+jupyterlite_contents = [
+   "*.ipynb",
+    "sprites/*.png",
+]
+
 master_doc = "index"
 source_suffix = ".rst"
 
@@ -29,4 +34,4 @@
 
 html_css_files = ["custom.css"]
 
-autodoc_member_order = "bysource"
+autodoc_member_order = "bysource"