[openbox] _NET_WM_STATE_BELOW doesn't work when set by an application

[R. Mattes]

On Wed, 5 Feb 2014 14:08:39 -0500, Dana Jansens wrote
> On Wed, Feb 5, 2014 at 1:56 PM, Danny <danny.smit.0 at gmail.com> wrote:
> [...]
> >>>> Hello,
> >>>>
> >>>> I'm using the default openbox (on gdm) on CentOS 6.5 and are working on an
> >>>> application (based on Qt 5.1.1) which tries to set one of its windows
to the
> >>>> background. The application uses the Qt API to achieve this. This should
> >>>> result in the windows manager flag _NET_WM_STATE_BELOW to be applied to the
> >>>> window. It seems that openbox doesn't react on this window manager flag.
> >>>>
> >>>> To come up with a simple test case, I tried the same with the Qt example
> >>>> "windowsflags". This results in the same behavior, the window doesn't seem
> >>>> to be kept below when the application asks for it.
> >>>>
> >>>> Additionally testing shows that this also aplies to Openbox 1.5.2, which
> >>>> is manually compiled from the sources.
> >>>>
> >>>> Furthermore, when using the openbox configure to set the specific window
> >>>> to the lowest layer, it does seem to work as expected, as long as the
> >>>> application itself doesn't ask to keep the window in the lowest layer.
> >>>>
> >>>> Another weird side effect is that the application is able to keep one
> >>>> window on top. However this doesn't work anymore if the same application
> >>>> also asks to keep another window below.
> >>>>
> >>>> Could this be a bug in openbox? Are there any suggestions how to proceed
> >>>> with this issue?
> >>>
> >>>
> >>> To change the state of a mapped window, a Client MUST send a _NET_WM_STATE
> >>> client message to the root window:
> >>>
> >>>   window  = the respective client window
> >>>   message_type = _NET_WM_STATE
> >>>   format = 32
> >>>   data.l[0] = the action, as listed below
> >>>   data.l[1] = first property to alter
> >>>   data.l[2] = second property to alter
> >>>   data.l[3] = source indication
> >>>
> >>>   other data.l[] elements = 0
> >>>
> >>> via http://standards.freedesktop.org/wm-spec/1.3/ar01s05.html

This isn't really helpfull for the OP since he/she uses Qt and does not
send raw messages to the server ....

> >>
> >> I noticed the Qt library uses xcb_change_property() calls to update
> >> the windows properties, which seem fine to me and also are working
> >> properly under gnome2.
> >>
> >> Is it correct to assume that if the obxprop command gives the
> >> following result on the window:
> >>
> >> _NET_WM_STATE(ATOM) = _NET_WM_STATE_FULLSCREEN, _NET_WM_STATE_BELOW,
> >> _OB_WM_STATE_UNDECORATED
> >>
> >> The messages are correctly applied and the window is expected to stay
> >> below the others?
> >
> > There is not much ambiguity in "MUST send a _NET_WM_STATE client
> > message to the root window".

Which neither answers any of the OP's questions nor helps in deciding who's
responisble for the described behaviour (OpenBox/libxcb/X).

I'm in a hurry, but a quick grep and a bit of Google shows that Qt provides
_two_ methods, QXcbWindow::setNetWmWindowFlags which only calls
xcb_change_property and QXcbWindow::changeNetWmState which _does_ send an event
to the root window.

 HTH Ralf Mattes