Cherry pick commits from master into April release#1560

Closed

DonJayamanne wants to merge 13 commits into

DonJayamanne:masterfrom

microsoft:mergeMasterIntoAprilRelease

Commits on Apr 10, 2020

Fix background (again) for ipywidgets (#11062) (#11064)
rchiodo
authored

Commits on Apr 11, 2020

Commits on Apr 13, 2020