[2.5][twksos] Datetime picker Expiration - Calendar jumping and other behavior

**Describe the bug**
From the Datetime picker:
1. The calendar jumps around randomly while scrolling through months/years.

2. Please see #2355 #2356 #2358

**To Reproduce**
Steps to reproduce the behavior:
**Note that the jumping seems to be contingent on months that have 6 weeks while most have 5 (see screenshots)**
1. Go to Exchange tab
2. Click on the BTS tab for BitCNY:BTS pair
3. Scroll down past the chart to buy/sell
4. Click on default expiration of 1 year
5. Click the default timedate shown noting a calendar popup
6. Attempt to click or scroll quickly through the months/years noting the calendar jumps around.

**Expected behavior**
A clear and concise description of what you expected to happen.
1. After clicking the default expiration (1 year) the user should be able to open the calendar either way of
clicking the currently shown datetime or clicking specific.
The user should be able to quickly click or scroll through the months/years while the calendar remains
stationary.
3. Consider moving the word "time" to the right closer to the time.
4. Consider adding a save (Done, or Close) button to the calendar as opposed to close on click of the selected date.
Previous releases were close on click (I think). Adding a save button allows the user to modify the
time if desired while the calendar is open (as opposed to closing upon clicking a date or year).
For illustration

**Screenshots**


**Desktop (please complete the following information):**
- OS: Windows 8.1
- Browser Opera
- Version 56.0.3051.116
- Release 181212rc-1

**Additional context**
I noticed while taking screenshots that if I clicked on the taskbar to open the snip tool OR anywhere else, the calendar would relocate. It prevented me from capturing the calendar shift but can be seen in the GIF capture.

Start by reproducing the datetime picker from the Exchange tab for a BitCNY:BTS pair, using the reported one-year expiration and rapid month or year navigation. Verify the calendar relocation and jumping behavior, including months with six weeks. Done means the calendar stays stable while navigating and the requested expiration and time-editing behavior is addressed.

Written by the indexing model from the issue text.