windowtype

Windowtype refers to the designation of a window's role or category within a graphical user interface. It is used by window managers and applications to determine how a window should be treated in terms of decorations, focus behavior, stacking order, and interaction with other windows. By signaling a window’s type, the system can apply rules appropriate to its purpose, such as keeping dialogs on top of their parents or treating tooltips differently from normal application windows.

In the X Window System, the concept is formalized through the _NET_WM_WINDOW_TYPE property, part of the Extended Window Manager Hints (EWMH). This property communicates the window type to the window manager by using atoms such as _NET_WM_WINDOW_TYPE_DESKTOP, _NET_WM_WINDOW_TYPE_DOCK, _NET_WM_WINDOW_TYPE_TOOLBAR, _NET_WM_WINDOW_TYPE_MENU, _NET_WM_WINDOW_TYPE_UTILITY, _NET_WM_WINDOW_TYPE_SPLASH, _NET_WM_WINDOW_TYPE_DIALOG, _NET_WM_WINDOW_TYPE_NORMAL, _NET_WM_WINDOW_TYPE_TOOLTIP, and _NET_WM_WINDOW_TYPE_NOTIFICATION. The exact set of values can vary by implementation, but these are among the commonly supported types. When a window manager recognizes a type, it can adjust behavior such as focus policy, icon placement, and whether the window appears on a specific virtual desktop.

Most modern toolkits (for example, GTK, Qt) expose an API to specify a window’s type so that the underlying window manager receives the correct hints. While the general concept is consistent, the terminology and available types may differ across platforms. See also: window manager hints, EWMH, GDK/Qt/GTK window type APIs.