qt-bugs@ issue : none yet

Trolltech task ID : none

bugs.kde.org number : none

applied: no

author: Lubos Lunak <l.lunak@kde.org>

 Hello,

 there are several problems with Qt's support for the WM_WINDOW_ROLE property:

- plain "QWidget w; w.setWindowRole( "test" );" aborts with 

Qt::WA_WState_Created not being set

- while QWidgetPrivate::create_sys() uses QObject object name for initial 

setting of WM_WINDOW_ROLE, later calls to QObject::setObjectName() have no 

effect on it

- Qt3 used the QObject object name for setting the window role, however Qt4 

uses some strange mix of object name and what's set manually with 

setWindowRole().

 The result is that that Qt3 and KDE3 apps that had WM_WINDOW_ROLE set don't 

in their Qt4 and KDE4 versions. I suggest using the attached patch which 

fixed all of the above problems:

- set explicit window role is used when actually set, otherwise the object 

name is used. This e.g. takes care of apps ported using setObjectName() from 

their Qt3/KDE3 versions (including e.g. Qt Designer) and generally makes it 

somewhat less demanding to actually set a usable window role (I can't quite 

see how many developers would be bothered to explicitly call 

setWindowRole()).

- calls to QObject::setObjectName() update the WM_WINDOW_ROLE property. Since 

QObjectPrivate already has a virtual dtor I think adding another virtual for 

handling the QWidget-related functionality from QtCore is fine.

--- src/corelib/kernel/qobject.cpp.sav	2007-05-29 14:07:18.000000000 +0200

+++ src/corelib/kernel/qobject.cpp	2007-06-15 16:03:39.000000000 +0200

@@ -994,9 +994,18 @@ void QObject::setObjectName(const QStrin

 {

     Q_D(QObject);

     d->objectName = name;

+#if defined(Q_WS_X11)

+    d->checkWindowRole();

+#endif

 }

+#if defined(Q_WS_X11)

+void QObjectPrivate::checkWindowRole()

+{

+}

+#endif

+

 #ifdef QT3_SUPPORT

 /*! \internal

     QObject::child is compat but needs to call itself recursively,

--- src/corelib/kernel/qobject_p.h.sav	2007-05-09 11:43:32.000000000 +0200

+++ src/corelib/kernel/qobject_p.h	2007-06-15 16:04:50.000000000 +0200

@@ -124,6 +124,9 @@ public:

     mutable quint32 connectedSignals;

     QString objectName;

+#if defined(Q_WS_X11)

+    virtual void checkWindowRole();

+#endif

 };

 class QSemaphore;

--- src/gui/kernel/qwidget_p.h.sav	2007-05-09 11:43:46.000000000 +0200

+++ src/gui/kernel/qwidget_p.h	2007-06-15 16:05:02.000000000 +0200

@@ -286,6 +286,7 @@ public:

 #if defined(Q_WS_X11)

     void setWindowRole(const char *role);

+    virtual void checkWindowRole();

     void sendStartupMessage(const char *message) const;

 #endif

--- src/gui/kernel/qwidget_x11.cpp.sav	2007-06-15 16:14:57.000000000 +0200

+++ src/gui/kernel/qwidget_x11.cpp	2007-06-15 16:28:06.000000000 +0200

@@ -619,11 +619,8 @@ void QWidgetPrivate::create_sys(WId wind

         // when we create a toplevel widget, the frame strut should be dirty

         data.fstrut_dirty = 1;

-        // declare the widget's object name as window role

-        QByteArray objName = q->objectName().toLocal8Bit();

-        XChangeProperty(dpy, id,

-                        ATOM(WM_WINDOW_ROLE), XA_STRING, 8, PropModeReplace,

-                        (unsigned char *)objName.constData(), objName.length());

+        // declare the widget's object name as window role if not set

+        setWindowRole( !q->windowRole().isEmpty() ? q->windowRole().toUtf8() : q->objectName().toUtf8());

         // set client leader property

         XChangeProperty(dpy, id, ATOM(WM_CLIENT_LEADER),

@@ -2617,12 +2614,20 @@ const QX11Info &QWidget::x11Info() const

 void QWidgetPrivate::setWindowRole(const char *role)

 {

     Q_Q(QWidget);

-    Q_ASSERT(q->testAttribute(Qt::WA_WState_Created));

+    if( !q->testAttribute(Qt::WA_WState_Created))

+        return;

     XChangeProperty(X11->display, q->internalWinId(),

                     ATOM(WM_WINDOW_ROLE), XA_STRING, 8, PropModeReplace,

                     (unsigned char *)role, qstrlen(role));

 }

+void QWidgetPrivate::checkWindowRole()

+{

+    Q_Q(QWidget);

+    if( q->windowRole().isEmpty())

+        setWindowRole( objectName.toUtf8());

+}

+

 Q_GLOBAL_STATIC(QX11PaintEngine, qt_widget_paintengine)

 QPaintEngine *QWidget::paintEngine() const

 {