# Dark window frame on Windows 10


From time to time I'm encountering a problem that app has dark color theme, but window frame is light. So here I'll save two ways to change it on Windows 10.

## For app users

I'll tell you right away: this way won't be useful if the accent color is important to you.

Open Registry Editor and find `HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\DWM` section. You'll need the following parameters from it:

* `ColorPrevalence`: DWORD = 1
  This parameter allows to use accent color as title bar color.
* `AccentColor` and `AccentColorInactive`: DWORD = color in ABGR format (hexadecimal).
  Colors for active and inactive mode.

Here's an example of registry file where color `#000000` is used for active window title and `#212121` is used for inactive one:

```reg
Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\DWM]
"ColorPrevalence"=dword:00000001
"AccentColor"=dword:ff000000
"AccentColorInactive"=dword:ff212121
```

## For app coders

You'll need [DwmSetWindowAttribute](https://learn.microsoft.com/en-us/windows/win32/api/dwmapi/nf-dwmapi-dwmsetwindowattribute) function:

```cs
HRESULT DwmSetWindowAttribute(
       HWND    hwnd,        // window
       DWORD   dwAttribute, // attribute itself
  [in] LPCVOID pvAttribute, // value
       DWORD   cbAttribute  // value size in bytes
);
```

Attribute values are described by [DWMWINDOWATTRIBUTE](https://learn.microsoft.com/en-us/windows/win32/api/dwmapi/ne-dwmapi-dwmwindowattribute) but we specifically interested in `DWMWA_USE_IMMERSIVE_DARK_MODE`. Documentation says it's equal to `20`, however until 20H1 version [the value has been equal to `19`](https://stackoverflow.com/a/62811758).

That's how i've tried to implement [autodetect of window frame theme in Ultimate++](https://github.com/ultimatepp/ultimatepp/pull/77):

```cpp
  HRESULT (WINAPI *DwmSetWindowAttribute)(HWND hwnd, DWORD dwAttribute, LPCVOID pvAttribute, DWORD cbAttribute);
  DllFn(DwmSetWindowAttribute, "dwmapi.dll", "DwmSetWindowAttribute");
  if (DwmSetWindowAttribute) {
    BOOL useDarkTheme = IsDarkTheme(); 
    DwmSetWindowAttribute(
      top->hwnd, 20, /* 20 is DWMWINDOWATTRIBUTE::DWMWA_USE_IMMERSIVE_DARK_MODE */
      &useDarkTheme, sizeof(useDarkTheme));
  }
```