(Filing a new bug here and marking the old one as duplicate because the old one was TL;DR and one can easily reproduce it with gtk3-demo-application.)

How to reproduce:
- run gtk3-demo-application
- write some text
- mark some text
- right click
  -> context menu opens, with first menu item 'Cut' not selected (correct
  behavior)
- click on the 'Cut' or 'Copy' menu entry

After that, the first menu entry will always be selected after right-clicking, provided the menu entry 'Cut' is active (= you have text selected).

I some applications the first entry of the right-click menu is always selected, even right after starting the application (like nautilus).

This happens with context-menus in every application I have tested so far: nautilus, evolution, totem, gnome-terminal ... and is a serious usability issue because 'slow' right-clicks trigger the first menu item.

Affected are gtk+ 3.2 and 3.4 (haven't tested 3.0).