Tkinter looks native on platforms that have native GUIs (Windows, macOS). On Unix you can use any of the numerous platform-independent (non-native) skins for Ttk:
The main issue with Tk/Ttk is mostly documentation and of course that it's a classic GUI framework, not a 3D-GPU-layer-based framework suitable for highly animated and composited UIs.
There's a bunch of stuff that you really wanna know about but simply isn't included in the Python docs, and the real API docs are for Tcl and you need to understand how those tclisms map over to Python.
IDLE uses the pre-ttk widget set and is indeed ugly.
See https://tkdocs.com/tutorial/idle.html for a case-study involving IDLE (Search for "Another Example" to see the settings window). You should be able to tell from the windows and mac screenshots how old this article is.
> The main issue with Tk/Ttk is mostly documentation and of course that it's a classic GUI framework, not a 3D-GPU-layer-based framework suitable for highly animated and composited UIs.
Those combo boxes are definitely not native. The menus are also off (the menu items are shorter and they turn blue instead of gray when highlighted).