I've installed Ubuntu 20 and the current version of Geany. When I press Shift+Alt+D, the date is always in the `DD.MM.YYYY` format.
This doesn't match my regional settings (English/Canada, trying to get the system to output YYYY-MM-DD), or the setting in Geany:
![image](https://user-images.githubusercontent.com/33569/81997322-4337fe00-9604-11ea-...)