Comment 3 for bug 1230172

So these settings are in the "app menu," which gets created in different places depending on the desktop environment. If the desktop environment (Unity) claims to support showing app menus, which Unity does, then Calculator intentionally does not show this menu in its window. In other desktops, Calculator will show this menu itself. Almost all GNOME apps behave the same way: there's nothing wrong with Calculator and there's nothing to fix in the Calculator code. (I guess the problem is that indicator-appmenu is apparently not a hard dependency of Unity, but I'm just guessing: I'm not sure how all these global menu packages work.) Anyway it should be "fixed" in 3.12 because I moved the mode setting from the app menu into the window. It's too important to hide up there. In 3.12 there is a gear menu on the left; in 3.14 the menu will be part of the window title [1].

I took a look at your blog post, and I see that you're editing C code that's output by the Vala compiler. The C code is provided only as a convenience so that you can build Calculator without installing the Vala compiler; it's not intended for editing. You really want to edit the Vala instead. It gets compiled into C when you type 'make'.

[1] http://fedoraftw.com/gnome-calculator-3132-received-interesting-changes