Created attachment 131836 [details]
In an empty spreadsheet I set A1-A20 to 2017-03-01 to 03-20, and set conditional formatting with condition: Date is / This week / Apply Style: Warning. This colors text in the relevant cells red.
Today is a beautiful Sunday (2017-03-12), and my locale is set to Hungarian (relevant detail: start of the week is Monday).
Bug: Calc considers week from Sunday to Saturday instead of Monday to Sunday (based on locale). See cells A12-A18 in attached screenshot.
Markus' comment from IRC:
<@moggi> bearon: good point with sunday vs monday, can you open a bug report? it is hard coded in the code
First version "Date is" option is available from is 18.104.22.168. Also tested with 22.214.171.124.
Looks as bug 70551.
*** This bug has been marked as a duplicate of bug 70551 ***
Hey Cor! How certain are you about these two bugs being the same? I was a bit surprised to find that WEEKS() is an add-in function (not sure what that means), and not part of the standard date/time functions.