Tkinter Treeview issue when inserting rows with tags

Question

I have just switched from python 3.6 to python 3.7. I have a function which inserts rows in a Treeview tree with tags. The tags are used for giving a foreground color and a background color to the rows inserted to the tree. My code was working ok when I was using python 3.6. Once I switched to 3.7 the rows inserted were not given a background or foreground color but where only given a white background and a black foreground color.

There doesn't seem to be a syntax change in tkinter.ttk from python 3.6 to 3.7 regarding tag configuration or tree insert.

tree.tag_configure('MATCHED', foreground='dark green', background='gray98')
tree.tag_configure('UNMATCHED', foreground='red2', background='gray98')

if match_status== '1':
    tree.insert('', 'end', text=df_row, values=my_value, tag='MATCHED')
elif match_status == '0':
    tree.insert('', 'end', text=df_row, values=my_value, tag='UNMATCHED')`

It is expected that when the rows are inserted to the tree to be given the correct background and foreground color.

Any help is appreciated.

Answer 1

Looks like the issue was caused by a newer version of tkinter, not a newer version of Python. This was reported in https://bugs.python.org/issue36468 and https://core.tcl-lang.org/tk/info/509cafafae

Here is a proposed solution. It should be both backward and forward compatible:

def fixed_map(option):
    # Fix for setting text colour for Tkinter 8.6.9
    # From: https://core.tcl.tk/tk/info/509cafafae
    #
    # Returns the style map for 'option' with any styles starting with
    # ('!disabled', '!selected', ...) filtered out.

    # style.map() returns an empty list for missing options, so this
    # should be future-safe.
    return [elm for elm in style.map('Treeview', query_opt=option) if
        elm[:2] != ('!disabled', '!selected')]

style = ttk.Style()
style.map('Treeview', foreground=fixed_map('foreground'), background=fixed_map('background'))