WM_NAME vs. _NET_WM_NAME

[Florian Bruhin]

* Martin Gräßlin <mgraesslin at kde.org> [2014-10-27 08:59:17 +0100]:
> > While developing a Qt application, I noticed some bugs regarding to
> > window title handling [1][2][3].
> 
> I assume that's Qt 5, right?

Indeed, it works fine with Qt 4.

> > It seems the Qt toolkit only sets _NET_WM_NAME and doesn't set WM_NAME
> > at all. Now that raises some questions:
> > 
> > - Should a client also set WM_NAME when setting _NET_WM_NAME? Sure,
> >   it's a good idea for backwards-compatiblity, but is it warranted to
> >   open a bug against Qt? (I'd say yes, but I'd like to hear other
> >   opinions).
> 
> From my reading of the relevant section in ICCCM (4.1.2.1) there is no 
> indication that a client is supposed to set it. Given that it's certainly not 
> a bug on Qt's side. If a window manager has problems with it, it's more 
> because the window manager doesn't support EWMH.

Okay. I'll still open a bug in Qt then since it seems to raise
problems in the wild - then it's up to them to decide whether it's
worth to fix it or not ;)

> Qt 5's XCB backend doesn't support many "deprecated" features where there is a 
> EWMH replacement. For example it also doesn't support setting a window icon 
> through the WM_HINTS (ICCCM section 4.1.2.4) property. Given that I 
> interpreted this as a design decision to not support the "deprecated" hints in 
> the new implementation.

Do you mean the backend as in a part of Qt, or xcb itself?

> At the same time knowing the Qt development I am sure they would accept 
> patches if it improves the interoperability.

I unfortunately don't feel comfortable enough with C++ to work on Qt
(I'm using PyQt).

> > - Should a window manager which implements EWMH act correctly when a
> >   client sets _NET_WM_NAME but not WM_NAME? (see [2])
> 
> I do not really understand this question. I looked at the bug report and would 
> say that's a hebstluftwm bug. For comparison KWin handles the situation with 
> Qt 5 windows correctly.

Okay. The question basically "is it the WM's fault, or Qt's fault" ;)

> Shameless plug: as you are using Qt 5, consider using KF5::WindowSystem which 
> is a nice Qt 5 (only, no further KDE dependencies) library implementing EWMH, 
> supporting fallback to ICCCM if needed. It's the library powering KWin and 
> Plasma (e.g. taskmanager) and also used in LXQt.

Probably not an option with PyQt, and also that's not really a
dependency I want to have just to set a window title :D

Thanks,

Florian

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