[Security] Update to PyQt5

As you know Qt4 is no longer receiving security updates, you should switch to Qt5 and its python bindings.
The switch from pyqt4 to pyqt5 should be relatively easy according to pyqt documentation on this topic (for example here).

[bmng-dev]

It is not so much PyQt but Qt itself that is the issue. Windows XP is still a supported platform for PyBitmessage. However Windows XP (and Vista) is missing from Qt5's Supported Platforms, although Qt for Windows - Specific Issues indicate it might be possible to build Qt5 for Windows XP. I understand @PeterSurda builds Qt4 as part of the release process so it is up to whether he can successfully build Qt5 and ensure everything still works on Windows XP before switching.

Qt4 is not maintained by the Qt project, when bugs are discovered, users can and will be hacked through the old Qt. Additionally, Windows XP is no longer LTS of Windows.
This is illogical.

Documentation / Upstream says it is possible to build Qt5 for XP.

Additional reading sources: https://doc.qt.io/qt-5/supported-platforms-and-configurations.html
"using Qt 5.6, XP will be supported until March 16, 2019"

Ping on the ticket.

@PeterSurda @bmng-dev do you plan to fix this at all, and if you will fix it what's the targeted version for this?
I also advise you to drop the idea of supporting an outdated, no longer supported, Microsoft system.

[bmng-dev]

Sorry @ghost, it's not up to me. I don't know why @PeterSurda hasn't responded.

[PeterSurda]

There are no specific plans, there are higher priority things. I'd prefer code that works both with Qt4 and Qt5 if possible, if someone submits a pull request I'll be happy to look at it.

[Lvl4Sword]

@bmng-dev I'm confused as to why XP/Vista would be supported at all, since those are EOL according to Microsoft ( and thus should be updated/replaced )
I stand by ghost's advice on not standing by these out-of-date systems

[bmng-dev]

@Lvl4Sword you and me both. I'm just someone who is interested in Bitmessage like you. I am not, nor have I ever been, involved in the decision making process of this project. At the time I responded to @ghost I thought Windows XP was supported because of things I had read from @PeterSurda (other issues here on github, on the forums, reddit, or on the bitmessage chan I can't remember) and tried to be helpful with a timely response anticipating what some of @PeterSurda concerns might be about moving to Qt5. The jury is still out on whether I'm correct or not.

[PeterSurda]

Just to clarify:

• at the moment, the backwards compatibility with Windows doesn't appear to create extra effort. I build the 32bit binaries on Windows 7, and while I do have a test environment for XP, I don't recall having problems since switching the build environment to Windows 7. Today's devel snapshot also works on Windows XP, even though I haven't done any tests on XP since releasing 0.6.2. I haven't really tested most of the post-0.6.2 changes on anything else than linux for that matter. It's possible that at some stage the backwards compatibility will break, and I'll make a decision at that time.

• the reason why I haven't switched to PyQt5 is that it's lower priority than other things. I don't know what the differences between Qt4 and Qt5 are and I'm not a UI specialist.

[a17r]

Please note that Qt4 and PyQt4 support is being dropped in distributions everywhere at this point, since being unmaintained for years.

[PeterSurda]

Sadly, I'm busy with more urgent issues and I've never used PyQt5 before. Maybe someone else can do that. @g1itch any interest?

[g1itch]

Actually I started already. And have first preview.