Windows 11’s native apps, such as File Explorer and other shell apps, use rounded corners and Fluent Design elements such as Acrylic by default. In addition to rounded corners, another important design feature of Windows 11 is materials such as Mica, which aligns the background color of apps with the desktop.
Mica is similar to acrylic, but works in a slightly different way. As Microsoft describes, Windows Mica material creates a “color hierarchy” by aligning the background with the application, trying to distinguish between multiple open instances of the app, such as File Explorer, etc.
Mica is essentially an opaque effect applied to certain areas of apps, such as windows and title bars. It’s a nice translucent effect, but Mica isn’t about transparency. Instead, just sample the desktop background to create a translucent effect that applies to title bars or windows.
Since Mica only samples the desktop background once and is not a transparency effect, it will not affect the performance of the system.
At this time, developers cannot enable this new material in their Win32 apps. However, this will soon change. As of Windows 11 version 22H2, developers can easily enable Mica or Acrylic in the container/window of their traditional Win32 apps, ie desktop programs.
This has been confirmed in a new document published by the company.
Mica lives in the Desktop Window Manager (DWM) and a new Windows 11 variable called “DWM_SYSTEMBACKDROP_TYPE” allows developers to specify Mica or acrylic material in their desktop apps.
“Flags for specifying the system-drawn background material of a window, including behind the non-customer area,” reads the support document. According to Microsoft, there are four constants developers can choose from:
- DWMSBT_AUTO: This is the default behavior. In this constant, Desktop Window Manager (DWM) automatically determines the background material drawn by the system for the app window.
- DWMSBT_NONE: Developers can skip Mica or Acrylic if they have their own app window design. Spotify, for example, comes with its own header. When this value is set, Microsoft does not draw a system background.
- DWMSBT_MAINWINDOW: Applies the background material effect that corresponds to a long-lived window.
- DWMSBT_TRANSIENTWINDOW: Applies the background material effect that corresponds to a temporary window.
- DWMSBT_TABBEDWINDOW: Applies the background material effect that corresponds to a window with a tabbed title bar.
As mentioned, Mica is part of Desktop Window Manager (DWM), making it available for a wide variety of apps. In fact, there is an open-source third-party tool called “Mica for everyone” which uses DwmSetWindowAttribute and other methods to force-enable Mica in any app.
While this update sounds like good news to everyone, there’s a catch. Microsoft says the new variable is exclusive to Windows 11 22H2 (Build 22621). In other words, if developers focus on earlier versions of the operating system, they are stuck with the old design.