Any symbols (including class properties) that should be visible
outside the module it's defined in need to be defined as global.
For now gjs still allows the access for 'const', but get rid of
the warnings spill now by changing it.
https://bugzilla.gnome.org/show_bug.cgi?id=785084
A lot of our modal dialogs share a similar structure:
[Icon] Some title
Maybe a subtitle
And sometimes even a body for stuff like
longer descriptions.
A dedicated widget with a common style will allow us to significantly
reduce duplication of both code and CSS.
https://bugzilla.gnome.org/show_bug.cgi?id=784985
This is the basic dialog actor implementation, which will allow us to
use the same implementation on the session-global modal dialogs. The
ModalDialog class now uses it underneath, and so do all users of it.
https://bugzilla.gnome.org/show_bug.cgi?id=762083
