I'm currently using yumex-dnf 4.3.3 on Fedora 25 x64 Workstation, with GNOME Shell Xorg session. When the packages list has focus, hitting Ctrl-A selects all packages. When the search bar has focus, hitting Ctrl-A selects all search text -- and also selects all currently listed packages. When the search bar has focus, Ctrl-A should *only* select the search text.
Oops, I somehow completely forgot that I'd already reported this problem. Herp. #1389207 *** This bug has been marked as a duplicate of bug 1389207 ***