Changing ttk.Style removes highlighting from ttk.Treeview

Question

I have tried building a treeview to store my data in tkinter, but unfortunately changing the style with ttk.Style completely removes the ability to highlight rows and the feature where columns are highlighted when hovered over.

Is there any way to fix this?

Example:

import tkinter as tk
from tkinter import ttk

inp = [{'Currency': 'EUR', 'Volume': '100', 'Country': 'SE'},
       {'Currency': 'GBP', 'Volume': '200', 'Country': 'SE'},
       {'Currency': 'CAD', 'Volume': '300', 'Country': 'SE'},
       {'Currency': 'EUR', 'Volume': '400', 'Country': 'SE'},
       {'Currency': 'EUR', 'Volume': '100', 'Country': 'DK'},
       {'Currency': 'GBP', 'Volume': '200', 'Country': 'DK'},
       {'Currency': 'CAD', 'Volume': '300', 'Country': 'DK'},
       {'Currency': 'EUR', 'Volume': '400', 'Country': 'DK'},
       ]


class Application(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.title("Volume")

        self.tree = ttk.Treeview(self, show='headings')
        columns = list(inp[0].keys())

        self.tree["columns"] = columns
        self.tree.pack(expand=tk.TRUE, fill=tk.BOTH)

        for i in columns:
            self.tree.column(i, anchor=tk.W)
            self.tree.heading(i, text=i, anchor=tk.W)

        for row in inp:
            self.tree.insert("", "end", values=list(row.values()))


root = Application()
style = ttk.Style()
style.theme_create('my_style', parent='clam')
style.theme_use('my_style')
root.mainloop()

Answer 1

For some reason I don't know, it seems like the created theme does not inherit from parent. Therefore your theme is missing among other settings the dynamic styling of the treeview's row.

To avoid that, it is simpler in my opinion to just modify an existing theme:

style = ttk.Style()
style.theme_use('clam')

style.configure(...)
style.map(...)