Applications using GNOME 3.30 runtime don't have a resize handle in the window border
I have noticed that applications using the GNOME 3.30 runtime from flathub do not have a resize handle when the mouse is near the window border, so there is no way to easily resize the window.
This happens for gedit, calendar, calculator but doesn't happen for hexchat, evolution, telegram. (the link seems to be that where it occurs they are using the GNOME 3.30 runtime).
My environment is the following and I'm using the X11 GNOME Shell session.
$ lsb_release -rd
Description: Ubuntu 18.04.1 LTS
Release: 18.04
$ flatpak --version
Flatpak 1.0.1