1880678 - Implement an initial UIController module to handle global variables

Status: ASSIGNED

(Thunderbird :: Mail Window Front End, task, P2)

Description

[Alessandro Castellani [:aleca]]

We have a lot of instances of globally scoped variables that are defined in one file and we use them, reassign them, release them, and so on, in multiple files.
It makes it impossible to guarantee a single source of truth and avoid sketchy solutions like reaching inside a window from another window to use those variables.
We should implement a generic UIController module which holds a singleton with the current always correct state of those variables, making them actually global and safe to use.

Comment 1

[Alessandro Castellani [:aleca]]

Attachment: Bug 1880678 - Implement a UI controller for global variables. r=#thunderbird-reviewers,darktrojan,freaktechnik

Purpose of this implementation
Start implementing a single UIController singleton that holds the correct reference of gFolder.
All files and implementations should use that singleton to get and set that gFolder in order to
guarantee always the correct state.

With this we can avoid passing that variable around by importing the same file, or assuming that
that file is available in the current window, and other not great paradigms.