xprop doesn't provide WM_CLASS

when running xprop and clicking on the VLC window

xprop | grep -i class

I get

WM_CLASS(STRING) = "", ""

but I expect sth like

"vlc, Vlc"

I use vlc ver. 0.9.6 on ArchLinux

Although this is not a major problem, I use xmonad as WM and it is very convenient that this feature is right. I am not 100% sure, but I believe it worked in the past.

Looks like a problem within Qt4.

assigned to @jbk

added Component::Interface: Qt label

Same problem here. It's a bit annoying in any window manager because it is impossible to give a certain geometry to the vlc window or to send it to a predefined virtual desktop.

I still don't find the issue.

Here, I get

WM_CLASS(STRING) = "Qt-subapplication", ""

but I somehow doubt Qt4 allows changing this.

It seems that the problem comes from a non standard use of Qt widgets, where QVLCFrames are not toplevel QWidgets. Returning to a more standard way may be difficult, so some low level X11 may be usefull, like :

XClassHint classHint;
classHint.res_name = const_cast<char*>("vlc");
classHint.res_class = const_cast<char*>("vlc");
XSetClassHint(QX11Info::display(), WId, &classHint);

to put in the right place, which I do not know right now.

Original author: Barna

QVLCFrame are QWidgets derivated and QVLCMW is a QMainWindow derivated, there is no reasons it doesn't work.

The reason is in qt function qt_init in qt4-x11-4.4.3/src/gui/kernel/qapplication_x11.cpp :

    if (X11->display) {
        // Qt part of other application

        // Set application name and class
        appName = qstrdup("Qt-subapplication");
        char *app_class = 0;
        if (argv) {
            const char* p = strrchr(argv[0], '/');
            app_class = qstrdup(p ? p + 1 : argv[0]);
            if (app_class[0])
                app_class[0] = toupper(app_class[0]);
        }
        appClass = app_class;
    } else {
        // Qt controls everything (default)

For some reason, QT thinks VLC is a sub-application, i.e. there is another application dealing with WM_CLASS stuff.

Original author: Barna

This simple patch makes

WM_CLASS(STRING) = "Qt-subapplication", ""

become

WM_CLASS(STRING) = "Qt-subapplication", "VLC"

diff --git a/modules/gui/qt4/qt4.cpp b/modules/gui/qt4/qt4.cpp
index 3d4cda2..2288c28 100644
--- a/modules/gui/qt4/qt4.cpp
+++ b/modules/gui/qt4/qt4.cpp
@@ -339,7 +339,7 @@ static void *Thread( void *obj )
 {
     intf_thread_t *p_intf = (intf_thread_t *)obj;
     MainInterface *p_mi;
-    char dummy[] = "";
+    char dummy[] = "VLC";
     char *argv[] = { dummy };
     int argc = 1;
 

Original author: Barna

Previous patch plus this one gives correct WM_CLASS, but this has in no way been tested further than `WM_CLASS is good'

diff --git a/modules/gui/qt4/util/qvlcapp.hpp b/modules/gui/qt4/util/qvlcapp.hpp
index b2a2ad6..8a51cee 100644
--- a/modules/gui/qt4/util/qvlcapp.hpp
+++ b/modules/gui/qt4/util/qvlcapp.hpp
@@ -35,7 +35,7 @@ public:
 
 #if defined (Q_WS_X11)
      QVLCApp( Display *dp, int & argc, char ** argv )
-         : QApplication( dp, argc, argv )
+         : QApplication( argc, argv )
      {
      }
 #endif

Original author: Barna

Well, courmisch should say ok or not, and I'll apply after that, since he was the one introducing this Display, so I am unsure if we can do that or not.

This patch breaks --x11-display. I'm not using the Display pointer just for fun.

I kind of expected that kind of answer :)

Is the --x11-display something else than standard Qt -display option ?

Original author: Barna

It's a VLC option used for all X11 connections (in all affected plugins).

assigned to @Courmisch and unassigned @jbk

added Status::fixed label

changed milestone to %1.0 bugs

closed

Fixed by f222f159