Partial updates of css and visible + simplification of widget_container
widget simplification continued
widget changes continued
correction
removing timout
adding options explicitly
making the use of options explicit
Merge pull request #6200 from SylvainCorlay/widget-changes

Partial update of DOMWidgetView styling and simplification of containers.
Fix kernelspec test skip condition

The code actually tries to write to /usr/local/share, but the test was
still checking for /usr/share. @minrk will test, as access to these
differs on his machine.
Merge pull request #6230 from takluyver/ks-test-check-usr-local

Fix kernelspec test skip condition
Use global event for celltoolbar
rename ipevents to events for consistency