Upgrade Bootstrap to later version

[Jaifroid]

Bootstrap 5 is now available (albeit in beta, but it is the currently recommended version). A significant advantage IMHO is that it now uses an open-source SVG-based icon library (which can be themed with CSS), and since we are looking to move towards a more icon-driven UI, we should consider this. I haven't yet checked out what is deprecated.

[Jaifroid]

Bootstrap 5 does not officially support IE11 or Edge <79, or Firefox <60. However, accoding to this repo, support for it can be added back for IE11 with some polyfills:

https://coliff.github.io/bootstrap-ie11/

IE11 is not EOL for another three years (surprisingly). We would need to be sure those polyfills also support the other browsers or webviews we currently support: Edge Legacy (although it is EOL in a couple of months, it lives on for now in the webviews for UWP apps), and the Firefox used in Firefox OS.

[Bam92]

Hi!

I'm wondering if this issue is going on well or does it need a help.

[Jaifroid]

@Bam92 This one is a bit complex, unless you have experience with Bootstrap. In particular, the lack of support for IE11 would complicate this upgrade (as in my previous comment). I suggest you work on #710 first, as it would get you familiar with the codebase.

[kelson42]

IE11 being now deprecated (see readme), what stopps us to move quickly on this?

[Jaifroid]

IE11 being now deprecated (see readme), what stops us to move quickly on this?

Two things:

• Deprecated doesn't mean we would consciously take steps that we know would prevent the app being used on a platform/browser. In this case, it would affect a wide range of browsers: Firefox < 60, Edge < 79 (hence the UWP app would stop working), as well as IE11. There is the possibility of using certain polyfills that might make it work on these platforms, but it needs investigation.
• Lack of time and person-power...

[Jaifroid]

I notice Bootstrap is now on Version 10! We are on Version 4 here. However, support for old browsers may well be a blocker in later versions, and our UI is quite simple, so upgrading may not bring any tangible benefit other than removing dependency on jQuery (see #921).