Apply new title bar themes in windows 11

[Akascape]

Try this: pywinstyles

Manual Settings if you need:

Apply the Mica theme

import sys
import customtkinter

customtkinter.set_appearance_mode("Dark")
root = customtkinter.CTk()

if sys.platform.startswith("win"):
    # Apply the mica theme for windows (works with win 11)
    from ctypes import windll, byref, sizeof, c_int
    HWND = windll.user32.GetParent(root.winfo_id())
    if sys.getwindowsversion().build < 22523:    
        windll.dwmapi.DwmSetWindowAttribute(HWND, 1029, byref(c_int(0x01)), sizeof(c_int))
    else:
        windll.dwmapi.DwmSetWindowAttribute(HWND, 35, byref(c_int(35)), sizeof(c_int))

root.mainloop()

Apply the Aero Theme

import customtkinter
from ctypes import POINTER, pointer, sizeof, windll, Structure
from ctypes.wintypes import DWORD, ULONG

customtkinter.set_appearance_mode("Dark")

class ACCENT_POLICY(Structure):
    _fields_ = [
        ('AccentState',   DWORD),
        ('AccentFlags',   DWORD),
        ('GradientColor', DWORD),
        ('AnimationId',   DWORD),
    ]

class WINDOW_COMPOSITION_ATTRIBUTES(Structure):
    _fields_ = [
        ('Attribute',  DWORD),
        ('Data',       POINTER(ACCENT_POLICY)),
        ('SizeOfData', ULONG),
    ]

def AeroEffect(hWnd):
    accentPolicy = ACCENT_POLICY()
    winCompAttr = WINDOW_COMPOSITION_ATTRIBUTES()
    winCompAttr.Attribute = 19 # also try with 6, 11, 30 (full transparent header), 
    winCompAttr.Data = pointer(accentPolicy)
    winCompAttr.SizeOfData = sizeof(accentPolicy)
    
    accentPolicy.AccentState = 3 # set 2 for default windows accent color
    windll.user32.SetWindowCompositionAttribute(hWnd, pointer(winCompAttr))
        
root = customtkinter.CTk()
root.title("")

HWND = windll.user32.GetParent(root.winfo_id())
AeroEffect(HWND)

root.mainloop()

Custom colors

import customtkinter
from ctypes import windll, byref, sizeof, c_int

root = customtkinter.CTk()

HWND = windll.user32.GetParent(root.winfo_id()) # the window we want to change

# These attributes are for windows 11 only 
DWMWA_CAPTION_COLOR = 35 # 35 is for title bar color
DWMWA_TITLE_COLOR = 36 # 36 is for title text
DWMWA_BORDER_COLOR = 34 # 34 is for window border color

# color should be in hex order: 0x00bbggrr
COLOR_1 = 0x00505000 # r: 00, b: 50, g: 50
COLOR_2 = 0x00FFFFFF # FF means full (100)
COLOR_3 = 0x00FFFF00 # r: full, g: full, b: 00

windll.dwmapi.DwmSetWindowAttribute(HWND, DWMWA_CAPTION_COLOR, byref(c_int(COLOR_1)), sizeof(c_int))
windll.dwmapi.DwmSetWindowAttribute(HWND, DWMWA_TITLE_COLOR, byref(c_int(COLOR_2)), sizeof(c_int))
windll.dwmapi.DwmSetWindowAttribute(HWND, DWMWA_BORDER_COLOR, byref(c_int(COLOR_3)), sizeof(c_int))

root.mainloop()

[Akascape]

Another way to get a windows native dark title bar:

import customtkinter
from ctypes import POINTER, pointer, sizeof, windll, Structure
from ctypes.wintypes import DWORD, ULONG

customtkinter.set_appearance_mode("Dark")

class ACCENT_POLICY(Structure):
        _fields_ = [
            ('AccentState',   DWORD),
            ('AccentFlags',   DWORD),
            ('GradientColor', DWORD),
            ('AnimationId',   DWORD),
        ]

class WINDOW_COMPOSITION_ATTRIBUTES(Structure):
        _fields_ = [
            ('Attribute',  DWORD),
            ('Data',       POINTER(ACCENT_POLICY)),
            ('SizeOfData', ULONG),
        ]

def ChangeAccent(hWnd):
        
        accentPolicy = ACCENT_POLICY()                                
        winCompAttrData = WINDOW_COMPOSITION_ATTRIBUTES()
        winCompAttrData.Attribute = 30
        winCompAttrData.SizeOfData = sizeof(accentPolicy)
        winCompAttrData.Data = pointer(accentPolicy)
        accentPolicy.AccentState = 1
                        
        windll.user32.SetWindowCompositionAttribute(hWnd, pointer(winCompAttrData))
                        
root = customtkinter.CTk()

HWND = windll.user32.GetParent(root.winfo_id())
ChangeAccent(HWND)

root.mainloop()

[Akascape]

Acrylic Theme

import customtkinter
from ctypes import POINTER, pointer, sizeof, windll, Structure, byref, c_int
from ctypes.wintypes import DWORD, ULONG


class ACCENT_POLICY(Structure):
        _fields_ = [
            ('AccentState',   DWORD),
            ('AccentFlags',   DWORD),
            ('GradientColor', DWORD),
            ('AnimationId',   DWORD),
        ]

class WINDOW_COMPOSITION_ATTRIBUTES(Structure):
        _fields_ = [
            ('Attribute',  DWORD),
            ('Data',       POINTER(ACCENT_POLICY)),
            ('SizeOfData', ULONG),
        ]

def ChangeAccent(hWnd: int, Color):
                                    
        accentPolicy = ACCENT_POLICY()  
                                    
        winCompAttrData = WINDOW_COMPOSITION_ATTRIBUTES()
        winCompAttrData.Attribute = 19
        winCompAttrData.SizeOfData = sizeof(accentPolicy)
        winCompAttrData.Data = pointer(accentPolicy)

        accentPolicy.AccentState = 4 # also try 6 for glass, 1 for accent
        accentPolicy.GradientColor = Color
                        
        windll.user32.SetWindowCompositionAttribute(hWnd, pointer(winCompAttrData))
                        
root = customtkinter.CTk()
                
HWND = windll.user32.GetParent(root.winfo_id())
color = 0x101010 # rgb order: 0xbbggrr
ChangeAccent(HWND, color)

root.mainloop()