The screen allows the user to change the default permission set,
that applies to every member (but not the owner nor the admins).
This screen is only accessible by the owner,
admins or members with the changeAdmin permission.
Added SingleChildScrollView to new-room, edit-room
and the about-room tab.
NOTE: Added a padding to the new and edit room pages,
to prevent widgets from touching the screen bottom
Data-fetch routine:
fetch room information from server
-> if unsuccessfull load room from disk
The room will automatically be closed,
if either of the following conditions apply:
- the user is offline and no data was found on disk
- the network request returned a server error
and rewrote the component's network requests.
showSimpleSnackbar, allows displaying a simple snackbar,
with text and one action button, that can be clicked.
doNetworkRequest is supposed to be a wrapper for the
already existing post* functions.
It aims to make network requests and error handling easier,
by containing all the try&catch blocks
and being able to show snackbars.
