The source project of this merge request has been removed.
UI: Follow GNOME HIG guidelines
According to GNOME HIG we should use Header Capitilazion for menu entries
"Header capitalization should be used for any headings, including headings in header bars, tab titles, and view titles. It should also be used for short control labels that do not normally form proper sentences, such as button labels, switch labels and menu items."
Source: https://developer.gnome.org/hig/guidelines/writing-style.html