7.0.X, 7.1.X, Master
Reproduction steps in IE11:
1) Login as admin
2) Add Calendar portlet
3) Create a test event including date & time
4) Modified the test event's date
The picker is shown as a drop-down under the date.
The picker appears in the middle of the window.
Reproduced on 7.0.x Commit: c5d0eff47a14f31a788d6bfc58d63ff9393eaf6d
Can't reproduce on Master, working as expected Commit: 6078ef910f410f601a1079dcbe65016232fe2f43