Instances are always displayed in one of the maximized,
minimized or normal states:
The modality of an instance may be specified using
style bits. The modality style bits are used to determine
whether input is blocked for other shells on the display.
The PRIMARY_MODAL style allows an instance to block
input to its parent. The APPLICATION_MODAL style
allows an instance to block input to every other shell in the
display. The SYSTEM_MODAL style allows an instance
to block input to all shells, including shells belonging to
Note: The styles supported by this class are treated
as HINTs, since the window manager for the
desktop on which the instance is visible has ultimate
control over the appearance and behavior of decorations
and modality. For example, some window managers only
support resizable windows and will always assume the
RESIZE style, even if it is not set. In addition, if a
modality style is not supported, it is "upgraded" to a
more restrictive modality style that is supported. For
example, if PRIMARY_MODAL is not supported,
it would be upgraded to APPLICATION_MODAL.
A modality style may also be "downgraded" to a less
restrictive style. For example, most operating systems
no longer support SYSTEM_MODAL because
it can freeze up the desktop, so this is typically
downgraded to APPLICATION_MODAL.
CLOSE | TITLE | MIN | MAX | RESIZE
TITLE | CLOSE | BORDER
Note: Only one of the styles APPLICATION_MODAL, MODELESS,
PRIMARY_MODAL and SYSTEM_MODAL may be specified.
IMPORTANT: This class is not intended to be subclassed.