Extended Window Manager Hints Explained

Extended Window Manager Hints, a.k.a. NetWM,^[1] is an X Window System standard for the communication between window managers and applications. It builds on the functionality of the Inter-Client Communication Conventions Manual (ICCCM).

These standards formulate protocols for the mediation of access to shared X resources, like the screen and the input focus. Applications request access, while the window manager grants or denies it. Communication occurs via X properties and client messages.The EWMH is a comprehensive set of protocols to implement a desktop environment. It defines both required and optional protocols. The window manager may choose to implement virtual desktops or a layered stacking order, but if it does, then the EWMH defines how this is communicated.

Protocol overview

All EWMH protocol identifiers start with the five letterprefix _NET_.

Root window properties

The WM must update a set of properties on the root window:

_NET_SUPPORTED : lists all the EWMH protocols supported by this WM.

_NET_CLIENT_LIST : lists all application windows managed by this WM.

_NET_NUMBER_OF_DESKTOPS : indicates the number of virtual desktops.

_NET_DESKTOP_GEOMETRY : defines the common size of all desktops.

_NET_DESKTOP_VIEWPORT : defines the top left corner of each desktop.

_NET_CURRENT_DESKTOP : gives the index of the current desktop.

_NET_DESKTOP_NAMES : lists the names of all virtual desktops.

_NET_ACTIVE_WINDOW : gives the currently active window.

_NET_WORKAREA : contains a geometry for each desktop.

_NET_SUPPORTING_WM_CHECK : gives the window of the active WM.

_NET_VIRTUAL_ROOTS : if the WM supports virtual root windows.

_NET_DESKTOP_LAYOUT : shows the layout of the active pager.

_NET_SHOWING_DESKTOP : is 1 for "showing the desktop" mode.

Client messages

An application may send client messages to a window manager:

_NET_WM_STATE : to change the state of an application window.

_NET_ACTIVE_WINDOW : to activate an application window.

_NET_SHOWING_DESKTOP : toggles display of application windows.

_NET_CLOSE_WINDOW : to close an application window.

_NET_WM_MOVERESIZE : to interactively resize an application window.

_NET_MOVERESIZE_WINDOW : to immediately resize an application window.

_NET_REQUEST_FRAME_EXTENTS : consults frame border dimensions.

_NET_WM_FULLSCREEN_MONITORS : defines the monitors for a fullscreen window.

If the WM supports window stacking:

_NET_RESTACK_WINDOW : asks to change the stacking order for a window.

If the WM supports virtual desktops:

_NET_CURRENT_DESKTOP : changes the current desktop.

_NET_NUMBER_OF_DESKTOPS : changes the number of desktops.

A WM may choose to ignore these messages:

_NET_DESKTOP_GEOMETRY : changes the dimension of all desktops.

_NET_DESKTOP_VIEWPORT : changes the viewport for the current desktop.

Window properties

The EWMH defines these application window properties:

_NET_WM_NAME : the title of the window.

_NET_WM_VISIBLE_NAME : the window title as shown by the WM.

_NET_WM_ICON_NAME : the title of the icon.

_NET_WM_VISIBLE_ICON_NAME : the icon title as shown by the WM.

_NET_WM_DESKTOP : the desktop the window is in.

_NET_WM_WINDOW_TYPE : the functional type of the window.

_NET_WM_STATE : the current window state.

_NET_WM_ALLOWED_ACTIONS : a list of supported user operations.

_NET_WM_STRUT : if the window wishes to reserve space at the edge.

_NET_WM_STRUT_PARTIAL : reserved space details at the screen edge.

_NET_WM_ICON_GEOMETRY : the geometry of a possible icon.

_NET_WM_ICON : an array of possible icons for the client.

_NET_WM_PID : the process ID of the client owning this window.

_NET_WM_HANDLED_ICONS : whether a pager provides icons.

_NET_WM_USER_TIME : time of last user activity in this window.

_NET_WM_USER_TIME_WINDOW : the window which shows user activity.

_NET_FRAME_EXTENTS : the left, right, top and bottom frame sizes.

_NET_WM_OPAQUE_REGION : which window regions are fully opaque.

_NET_WM_BYPASS_COMPOSITOR : requests that the window is uncomposited.

Window states

The ICCCM defines only three distinct states a window can be in:

1. Withdrawn,
2. Normal,
3. Iconic.

In addition it supports an Urgent flagto request user attention.

The EWMH defines thirteen window state flags:

• Above: show the window above others,
• Below: show the window below others,
• DemandsAttention: same as the urgent flag,
• Focused: the window has input focus,
• Fullscreen: show the window fullscreen,
• Hidden: the window is unmapped,
• MaximizedHorizontal: the window is stretched horizontally,
• MaximizedVertical: the window is stretched vertically,
• Modal: the window is a modal popup,
• Shaded: the window is rolled up,
• SkipPager: the window should not be shown on a pager,
• SkipTaskbar: the window should be ignored by a taskbar,
• Sticky: the window should be shown on all virtual desktops.

Additional protocols

_NET_WM_PING : a WM can use this to test if a client is alive.

_NET_WM_SYNC_REQUEST : for synchronizing repaints when resizing.

_NET_WM_FULL_PLACEMENT : the WM will handle any window placement.

List of window managers that support Extended Window Manager Hints

Tiling and dynamic window managers

• aewm
• awesome
• bspwm
• echinus^[2]
• fvwm
• goomwwm
• herbstluftwm
• i3^[3]
• LeftWM
• Notion^[4]
• Qtile
• spectrwm
• subtle^[5]
• Wingo^[6]
• wmii
• xmonad (needs to be turned on in the config)

Stacking window managers

• Blackbox^[7]
• Compiz
• CTWM (as of 4.0.0^[8])
• edewm
• Fluxbox^[9]
• FVWM (via a plugin prior to v2.4 and native support from v2.5)^{[10] [11]}
• IceWM^[12]
• JWM^[13]
• KWin
• Metacity^[14]
• Marco
• Openbox^[15]

Other window managers

• Enlightenment (E16 and E17)
• evilwm
• interfacewm
• matchbox
• Sawfish (not completely)
• wmfs
• Xfwm^[16]

External links

• • The Window Manager Specification Project at freedesktop.org
• Extended Window Manager Hints Support For FVWM

Notes and References

1. Web site: Net WM - Blackbox . 2007-09-29 . https://web.archive.org/web/20071001170417/http://blackboxwm.sourceforge.net/NetWM . 2007-10-01 . dead .
2. Web site: polachok/echinus: README - 3. About panels and pagers. . 2022-08-19.
3. Web site: i3 _NET_SUPPORTED. . 2021-02-14.
4. Web site: Fixed _NET_SUPPORTING_WM_CHECK and _NET_SUPPORTED property setup.. . 2022-08-19.
5. Web site: What is subtle?. 2022-08-19.
6. Web site: BurntSushi/wingo: COMPLIANCE - EWMH. . 2022-08-19.
7. Web site: Blackbox COMPLIANCE. . 2021-02-15 .
8. Web site: ctwm 4.0.0 changes.
9. Web site: Fluxbox EWMH Support . 2009-09-09 . 2009-08-19 . https://web.archive.org/web/20090819040039/http://fluxbox.sourceforge.net/docs/ewmh-support.html . dead .
10. Web site: Extended Window Manager Hints Support For FVWM.
11. Web site: FVWM - Features.
12. Web site: IceWM COMPLIANCE. . 2020-12-28 .
13. Web site: joewing.net | JWM EWMH Support. 2021-02-15.
14. Web site: Metacity COMPLIANCE . 2021-02-15.
15. Web site: Openbox COMPLIANCE . . 2021-02-15.
16. https://docs.xfce.org/xfce/xfwm4/standards xfwm4 standards