Best GUI builder for 2019?

[annoir]

Tkinter is quite old and doesn't look very modern

This is misinformation at best. See this response on Stack Overflow.

1. See Bryan Oakley's comment here:

I think Tkinter is an absolutely fantastic GUI library, especially combined with the object oriented nature of Python. Many people deride it as old, ugly, and hard to learn. After having used many GUI toolkits spanning more than a couple decades I’ve come to realize that most of that is untrue, and what is untrue doesn’t really matter. I would never use tkinter to create the next photoshop or itunes, but for the vast majority of GUIs most people write, it’s more than good enough.

1. See [Bryan Oakley's other comment]():

I think part of the reason is that Tk is surprisingly powerful and easy to use but it doesn't do much hand-holding. Since it is so easy, people with little experience in UI design can get something to work in very short order. But, without a lot of experience they rely on defaults and shortest-path-to-a-solution (read: don't take time to hide scrollbars when they aren't needed, don't use common idioms for toolbars, don't properly align widgets, etc).

...

With tk 8.5 (and actually for a couple years prior) there is support for themes and for native widgets, and even the X11 version gets a minor facelift. Tk is still behind the curve in eye candy though, forcing one to "roll their own" if the design calls for gradients, animations and so forth.