At some point we likely want to drop support for Qt4, to be able to use new Qt5 features without worrying about backwards compatibility.
Not sure when: there is no real hurry. Just wanted to have a issue open for this. This doesn't have to be 0.14. Although the number of people still testing with Qt4 is likely very low.
The only article I could find on Qt's EOL policy was: https://blog.qt.io/blog/2014/11/27/qt-4-8-x-support-to-be-extended-for-another-year/ which is pretty old.
IMO anything like this should wait for KDE 5 to be mostly viable as an upgrade for KDE 4. At least, last I checked, that is still a bit off (but coming up fast, maybe within a year).
You can't use Qt5 applications on KDE4?
Not without losing native platform integration, unfortunately. :(
Ok let's wait for that then.
See-also #9038. The PPA was forced to revert to Qt4.
I think that post Bitcoin 0.16, dropping support for QT4 can be seriously reconsidered.
KDE 4 is basically dead nowadays.
AFAIK the only reasons to keep Qt4 support are "because why not" and some PPA issue (unless that's been resolved?).
I'm not aware of any changes that would allow us to reconsider dropping Qt4 support. Ultimately we probably can't do that until we drop the tray bar icon (which is probably a thing we should do anyway, its a pretty strange thing to have anymore, AFAIU).
Maybe I'm old-fashioned, but I seem to have a number of tray icons from apps on all the OSes I use, and I never had any real issues with them. Is the problem specific to Unity and/or a particular version? I can't quite make that out from the linked tickets
Yes, it is specific to the interaction of unity and tray icons (which requires a plugin to work properly, which has been broken for a long time and will never be fixed). With any other window manager there should be no problem.
If that's really the only thing holding this back, maybe we should add a configure option so that @TheBlueMatt can disable the tray icon for PPA builds. On older ones, as newer Ubuntu don't use unity anymore.
Tentatively moving this to 0.17.0, given that we can address @TheBlueMatt 's issue in one way or another.
Well we can at least deprecate it in 2021 when 16.04 LTS isnt supported anymore :/. Disabling functionality in the PPA seems like a super weird way to address this issue.
That's fine, whatever you want, but we're not going to wait that long to deprecate Qt4, just because of a minor annoyance with a small detail in the GUI on some distros.
From what I read in the quassel IRC channel, apparently Gentoo is going to drop Qt4 support very soon. Other distros will likely follow.
Given how few people are working on QT, not having to think about Qt4 would probably speed up UI development. It's still a cause for confusion e.g. #12723 (comment)
I'd also prefer to kill it in 0.17 and deal with "minor annoyance with a small detail in the GUI on some distros" directly if someone can turn those into Github issues.
I'm in favour of dropping Qt4 support completely (for 0.17). It may restrict the possible OS set. The try icon issue (https://github.com/bitcoin/bitcoin/issues/9038) seems to be fixed.
Since this obviously only affects the GUI part (and not bitcoind), I think limiting (very little to none in future) the possible OSes seems acceptable.
Milestone
0.17.0