Window manager "Urgency" hint is ignored for domU windows

[keepiru]

Qubes OS version (e.g., R3.2):

R3.2

Affected TemplateVMs (e.g., fedora-23, if applicable):

Any

---

Expected behavior:

Taskbar icon ("Window Button") blinks when WM_HINTS urgency bit is set.

Actual behavior:

Urgency is handled correctly for dom0 windows, but ignored for domU.

Steps to reproduce the behavior:

Repro (a):

urgent_hello.c.txt
In an AppVM:
$ gcc -L/usr/X11R6/lib -lX11 urgent_hello.c
$ ./a.out

When the window opens, alt-tab away so it is backgrounded. After two seconds the urgency hint will be set. Observe that taskbar icon does not blink.

Copy a.out to dom0 and repeat. Observe that the taskbar icon blinks as expected.

Repro (b):
Launch xterm in dom0.
Control-middle_click, check "Enable Bell Urgency"
$ sleep 2 ; echo -e '\a'
Alt-tab to background the window.
Observe blinking taskbar icon.
Repeat in AppVM. Observe non-blinking taskbar icon.

General notes:

https://github.com/QubesOS/qubes-issues/files/784748/urgent_hello.c.txt
https://tronche.com/gui/x/icccm/sec-4.html#WM_HINTS
https://specifications.freedesktop.org/wm-spec/wm-spec-latest.html#URGENCY

---

Related issues:

[andrewdavidwong]

@marmarek, is this intentional?

[marmarek]

Clearly this window manager hint is not supported, but I'm not sure if it should be. For example, will it make easier for application to steal the focus?

[keepiru]

I think it should be supported. Many applications use it: Email and IM clients to indicate new messages are waiting; terminals to indicate a bell.

My use case is instant messaging. I'm failing to notice PMs when the window is hidden.

The flag is used for window decoration and taskbar highlights to attract the user's attention, but focus is not automatically changed; the user has to do so manually, at least in every window manager I've used. XFWM4 certainly doesn't use it to change focus. You can test this by setting the flag on dom0 windows.

[marmarek]

Something very similar is supported: _NET_WM_STATE_DEMANDS_ATTENTION flag:
https://specifications.freedesktop.org/wm-spec/1.3/ar01s05.html

Maybe support for "urgency" flag could be plugged into the same feature?

[aidecoe]

@marmarek Could you suggest in which component it should be implemented, please?

[marmarek]

Dom0 part: https://github.com/QubesOS/qubes-gui-daemon/
VM part: https://github.com/QubesOS/qubes-gui-agent-linux/
Related protocol part: https://github.com/QubesOS/qubes-gui-common/blob/master/include/qubes-gui-protocol.h#L198-L204
Not sure how "Urgency" is different from "Demands attention", but if they are in practice the same, maybe this thing could be merged? I.e. at gui-agent side set the flag if either of them is set and in gui-daemon - set both. This would reduce number of possible flags combinations controllable by VM (Xorg is full of corner cases),

[donob4n]

Maybe this could be handled from dom0 like fullscreen. Only trusted domains are allowed to steal focus.

[marmarek]

I think no qube should be allowed to steal focus. This is a bit tricky, even without this urgency flag implemented (see various window manager settings), but lets not make things even worse.

[aidecoe]

Urgency has nothing to do with stealing focus, IIUC. Window notifies window manager that it needs attention, but the window is not brought up. In e.g. dwm, awesome or i3 the effect is that window title and tag on which the window has signaled "urgency" is highlighted. Nothing more. "Urgency" would be implemented similarly as "demands attention".

[keepiru]

UrgencyHint is defined in ICCCM, and is only cleared by the application.

_NET_WM_STATE_DEMANDS_ATTENTION is defined by EMWH, and is cleared by the WM when the window receives focus.

In all other respects they're essentially the same thing. XFCE4 already implements both flags, so I think all that's required is for qubes-guid to copy the flags back and forth.