Inside Macintosh: Macintosh Toolbox Essentials
When it creates a window, the Window Manager places a value in the windowKind field of a window record that identifies how the window was created; see "The Color Window Record" for details. The windowKind field typically contains one of these values:
enum { /* new names for dialog kind enumerators */
kDialogWindowKind = 2, /* dialog or alert window */
kApplicationWindowKind = 8 /* window created by an
/* application */
};
enum { /* old names for dialog kind enumerators */
dialogKind = 2, /* dialog window */
userKind = 8 /* user window */
};