Description:
In Calc, when you hover the mouse pointer over the red dot of a cell with a comment, the comment is displayed in a popup. This popup has a drop shadow on its right and bottom sides, and sometimes on top. After the mouse pointer is removed, the popup closes, but the drop shadow is not removed, it remains visible over the contents of the cells under it.

Clicking on a cell under the shadow, removes the part of the shadow (right side or bottom/top) that is in the region of clicking. Sometimes clicking in other random cells may also remove the shadow (partly or fully).


Steps to Reproduce:
1.In Calc insert a comment to any cell
2.Click on an empty cell to close the comment popup
3.Hover the mouse pointer over the red dot of the cell with the comment.  The comment will popup.
4.Move the mouse pointer away from the red dot/cell. The comment popup closes, but the drop shadow remains visible.
5.Start clicking in cells that are covered with the drop shadow. The shadow disappears.

Actual Results:  
Comment drop shadow remains visible, after comment popup closes.

Expected Results:
Comment drop shadow be removed together with the closing of the comment popup.


Reproducible: Always

User Profile Reset: No

Additional Info:
[Information automatically included from LibreOffice]
Locale: en-US
Module: SpreadsheetDocument
[Information guessed from browser]
OS: Windows 10
OS is 64bit: yes
Builds ID: LibreOffice 5.3.6.1


User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36