This attribute can be used to globally change the default image type for attributes such
as Button.Icon or Toolbarbutton.Icon to icon instead of brush.
Even though the names of those attributes might suggest otherwise, they indeed expect a
Hollywood brush by default for historical reasons. Using Hollywood icons, however, is often
more convenient because they offer greater flexibility, especially when it comes to high-DPI support,
which is why using Hollywood icons instead of brushes is often preferred by GUI designers nowadays.
See High-DPI support for details.
Alternatively, you can also change the default image type from brush to icon on
a per-widget basis by using attributes such as Button.IconType or
Toolbarbutton.IconType but doing this globally using Application.UseIcons
might be more convenient.