Why umask is not honoured in Gnome environment ?

Issue

• Even when setting a user's umask to be more permissive than 022 (the default), such as 007, this more permissive umask is not respected by any application that's started from the Gnome desktop.
• Files written with LibreOffice (or gedit for that matter) are still created with a 022 umask.
• Any file written by any desktop application appears to be written with the incorrect umask.
• This happens for all files written through a Gnome GUI application. Creating files from a terminal are written with the correct permissions.