I tried to start Gitkraken on Gnome, but it says:
Gtk-Message: Failed to load module "pantheon-filechoosser-module"
It seems you're trying to run an ElementaryOS application outside of ElementaryOS, which is somewhat unsupported.
You can ignore the failure to load a GTK module warning, in general; it means something is trying to delegate some functionality to an external module, and it won't work. Of course, an application may implicitly rely on that functionality; in that case, you'll have to contact the author of the application and ask them if the application can run on different platforms.