Windows 11’s native apps like File Explorer and other shell
apps use rounded corners and Fluent Design elements like
Acrylic by default. In addition to rounded corners, another
important design feature of
Windows 11 is materials like Mica which aligns the
background colour of apps with the desktop.
Mica is similar to Acrylic, but it works in a slightly
different manner. As Microsoft describes, Windows Mica material
creates a “colour hierarchy” by aligning the background with
the application, in a bid to distinguish between multiple open
instances of the app like File Explorer, etc.
Mica is essentially an opaque effect that’s applied to select
areas of apps, such as windows and title bars. It’s a fancy
translucent effect, but Mica is not about transparency.
Instead, samples the desktop wallpaper only to create a
translucent effect that applies to title bars or windows.
Since Mica samples the desktop wallpaper only once and is not a
transparency effect, it doesn’t affect the performance of the
At the moment, developers cannot enable this new material in
their Win32 apps. However, this is set to change soon. Starting
with Windows 11 version 22H2, developers can easily enable Mica
or Acrylic in the container/window of their traditional Win32
apps i.e desktop programs.
This has been confirmed in a new document published by the company.
Mica lives inside the Desktop Window Manager (DWM) and a new
Windows 11 variable called “DWM_SYSTEMBACKDROP_TYPE” will allow
developers to specify Mica or Acrylic material in their desktop
“Flags for specifying the system-drawn backdrop material of a
window, including behind the non-client area,” the support
document reads. As per Microsoft, there are four constants that
developers can choose from:
- DWMSBT_AUTO: This is the default behaviour. In this
constant, Desktop Window Manager (DWM) will automatically
decide the system-drawn backdrop material for the app’s window.
- DWMSBT_NONE: Developers can skip Mica or Acrylic if they’ve
their custom design for the app window. For example, Spotify
comes with its own header. When this value is set, Microsoft
won’t don’t draw any system backdrop.
- DWMSBT_MAINWINDOW: Applies the backdrop material effect
corresponding to a long-lived window.
- DWMSBT_TRANSIENTWINDOW: Applies the backdrop material
effect corresponding to a transient window.
- DWMSBT_TABBEDWINDOW: Applies the backdrop material
effect corresponding to a window with a tabbed title bar.
As mentioned, Mica is a part of the Desktop Window Manager
(DWM), which makes it available to a wide range of apps. In
fact, there’s a third-party open-source tool called “Mica for
Everyone” which uses DwmSetWindowAttribute and other
methods to force enable Mica in any app.
While this update sounds like a piece of good news for
everyone, there’s a catch. Microsoft says the new variable is
exclusive to Windows 11 22H2 (Build 22621). In other words, if
developers are targeting prior versions of the OS, they’re
stuck with the old design.