This issue duplicates another issue.
Ext JS Premium Member
data-qtip, and tooltip is cut in in ExtJS 4.2.0
It looks like there is an issue with tooltips in ExtJS 4.2.0 I tried to upgrade my app written with 4.1.3 to 4.2.0 and saw a tooltip issue. But then figured out that same issue exist even in extjs example pages.
Tried with latest chrome browser:
It looks like that tip size is fixed.
Thanks for the report!
Looks like there is an open bug report on this one: