xcb: cleanup _MOTIF_WM_HINTS handling

The existing code was difficult to follow, it contained some code
duplication, inconsistencies and legacy code (mwm/dtwm support).
Most of this code was copied over from Qt 4 as is, with some
unexplainable (accidental?) modifications.

Most of Motif code was never ported over to Qt5. In addition to the
properties and protocols described in ICCCM, Motif uses properties
and protocols of its own. In Qt4 we had an implementation of Motif
DnD protocol. This was never ported over and mentions of this support
was removed on Oct 2012, 4c41cb48d0356a28190c300fd4cc5e03f824b870.
Nobody has complained for all these years, so it is safe to remove
the remaining leftovers. Motif style support also was removed around
the same time 4c41cb48d0356a28190c300fd4cc5e03f824b870.

Keeping only those Motif hints that do not have any replacement in
modern window manager specifications - decorations hints.
MWM_INPUT_*MODEL* in modern specs was replaced by _NET_WM_STATE_MODAL

The existing code was setting _MOTIF_WM_HINTS from 2 places - from
QWindow setter (::setWindowFlags) and again before mapping the window
(::show). We don't need the logic from updateMotifWmHintsBeforeMap().
That function read the current value of _MOTIF_WM_HINTS and merged in
few additional hints, hints that are not relevant based on all the
reasons from above.

Change-Id: I9cb10bcad9bfac8762e3909895c2e9de613e622c
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

4 files changed, 18 insertions, 139 deletions

diff --git a/src/plugins/platforms/xcb/qxcbatom.cpp b/src/plugins/platforms/xcb/qxcbatom.cpp
index 9255a57a4f..ecb73cb90b 100644
--- a/src/plugins/platforms/xcb/qxcbatom.cpp
+++ b/src/plugins/platforms/xcb/qxcbatom.cpp
@@ -183,16 +183,6 @@ static const char *xcb_atomnames = {
     "XdndActionMove\0"
     "XdndActionPrivate\0"
 
-    // Motif DND
-    "_MOTIF_DRAG_AND_DROP_MESSAGE\0"
-    "_MOTIF_DRAG_INITIATOR_INFO\0"
-    "_MOTIF_DRAG_RECEIVER_INFO\0"
-    "_MOTIF_DRAG_WINDOW\0"
-    "_MOTIF_DRAG_TARGETS\0"
-
-    "XmTRANSFER_SUCCESS\0"
-    "XmTRANSFER_FAILURE\0"
-
     // Xkb
     "_XKB_RULES_NAMES\0"
 
diff --git a/src/plugins/platforms/xcb/qxcbatom.h b/src/plugins/platforms/xcb/qxcbatom.h
index b6cc159035..233d2eadb7 100644
--- a/src/plugins/platforms/xcb/qxcbatom.h
+++ b/src/plugins/platforms/xcb/qxcbatom.h
@@ -184,16 +184,6 @@ public:
         XdndActionMove,
         XdndActionPrivate,
 
-        // Motif DND
-        _MOTIF_DRAG_AND_DROP_MESSAGE,
-        _MOTIF_DRAG_INITIATOR_INFO,
-        _MOTIF_DRAG_RECEIVER_INFO,
-        _MOTIF_DRAG_WINDOW,
-        _MOTIF_DRAG_TARGETS,
-
-        XmTRANSFER_SUCCESS,
-        XmTRANSFER_FAILURE,
-
         // Xkb
         _XKB_RULES_NAMES,
 
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index f36bb5a51e..e56f6b13d8 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -118,8 +118,6 @@ enum {
     defaultWindowHeight = 160
 };
 
-//#ifdef NET_WM_STATE_DEBUG
-
 QT_BEGIN_NAMESPACE
 
 Q_DECLARE_TYPEINFO(xcb_rectangle_t, Q_PRIMITIVE_TYPE);
@@ -756,9 +754,6 @@ void QXcbWindow::show()
         if (!transientXcbParent)
             xcb_delete_property(xcb_connection(), m_window, XCB_ATOM_WM_TRANSIENT_FOR);
 
-        // update _MOTIF_WM_HINTS
-        updateMotifWmHintsBeforeMap();
-
         // update _NET_WM_STATE
         updateNetWmStateBeforeMap();
     }
@@ -909,8 +904,6 @@ void QXcbWindow::doFocusOut()
 
 struct QtMotifWmHints {
     quint32 flags, functions, decorations;
-    qint32 input_mode;
-    quint32 status;
 };
 
 enum {
@@ -932,50 +925,8 @@ enum {
     MWM_DECOR_MENU     = (1L << 4),
     MWM_DECOR_MINIMIZE = (1L << 5),
     MWM_DECOR_MAXIMIZE = (1L << 6),
-
-    MWM_HINTS_INPUT_MODE = (1L << 2),
-
-    MWM_INPUT_MODELESS                  = 0L,
-    MWM_INPUT_PRIMARY_APPLICATION_MODAL = 1L,
-    MWM_INPUT_FULL_APPLICATION_MODAL    = 3L
 };
 
-static QtMotifWmHints getMotifWmHints(QXcbConnection *c, xcb_window_t window)
-{
-    QtMotifWmHints hints;
-
-    auto reply = Q_XCB_REPLY_UNCHECKED(xcb_get_property, c->xcb_connection(), 0, window,
-                                       c->atom(QXcbAtom::_MOTIF_WM_HINTS), c->atom(QXcbAtom::_MOTIF_WM_HINTS), 0, 20);
-
-    if (reply && reply->format == 32 && reply->type == c->atom(QXcbAtom::_MOTIF_WM_HINTS)) {
-        hints = *((QtMotifWmHints *)xcb_get_property_value(reply.get()));
-    } else {
-        hints.flags = 0L;
-        hints.functions = MWM_FUNC_ALL;
-        hints.decorations = MWM_DECOR_ALL;
-        hints.input_mode = 0L;
-        hints.status = 0L;
-    }
-
-    return hints;
-}
-
-static void setMotifWmHints(QXcbConnection *c, xcb_window_t window, const QtMotifWmHints &hints)
-{
-    if (hints.flags != 0l) {
-        xcb_change_property(c->xcb_connection(),
-                            XCB_PROP_MODE_REPLACE,
-                            window,
-                            c->atom(QXcbAtom::_MOTIF_WM_HINTS),
-                            c->atom(QXcbAtom::_MOTIF_WM_HINTS),
-                            32,
-                            5,
-                            &hints);
-    } else {
-        xcb_delete_property(c->xcb_connection(), window, c->atom(QXcbAtom::_MOTIF_WM_HINTS));
-    }
-}
-
 QXcbWindow::NetWmStates QXcbWindow::netWmStates()
 {
     NetWmStates result(0);
@@ -1004,9 +955,7 @@ QXcbWindow::NetWmStates QXcbWindow::netWmStates()
         if (statesEnd != std::find(states, statesEnd, atom(QXcbAtom::_NET_WM_STATE_DEMANDS_ATTENTION)))
             result |= NetWmStateDemandsAttention;
     } else {
-#ifdef NET_WM_STATE_DEBUG
-        printf("getting net wm state (%x), empty\n", m_window);
-#endif
+        qCDebug(lcQpaXcb, "getting net wm state (%x), empty\n", m_window);
     }
 
     return result;
@@ -1079,22 +1028,18 @@ void QXcbWindow::setWindowFlags(Qt::WindowFlags flags)
 
     setWmWindowType(wmWindowTypes, flags);
     setNetWmStateWindowFlags(flags);
-    setMotifWindowFlags(flags);
+    setMotifWmHints(flags);
 
     setTransparentForMouseEvents(flags & Qt::WindowTransparentForInput);
     updateDoesNotAcceptFocus(flags & Qt::WindowDoesNotAcceptFocus);
 }
 
-void QXcbWindow::setMotifWindowFlags(Qt::WindowFlags flags)
+void QXcbWindow::setMotifWmHints(Qt::WindowFlags flags)
 {
     Qt::WindowType type = static_cast<Qt::WindowType>(int(flags & Qt::WindowType_Mask));
 
     QtMotifWmHints mwmhints;
-    mwmhints.flags = 0L;
-    mwmhints.functions = 0L;
-    mwmhints.decorations = 0;
-    mwmhints.input_mode = 0L;
-    mwmhints.status = 0L;
+    memset(&mwmhints, 0, sizeof(mwmhints));
 
     if (type != Qt::SplashScreen) {
         mwmhints.flags |= MWM_HINTS_DECORATIONS;
@@ -1152,7 +1097,18 @@ void QXcbWindow::setMotifWindowFlags(Qt::WindowFlags flags)
         mwmhints.decorations = 0;
     }
 
-    setMotifWmHints(connection(), m_window, mwmhints);
+    if (mwmhints.flags) {
+        xcb_change_property(xcb_connection(),
+                            XCB_PROP_MODE_REPLACE,
+                            m_window,
+                            atom(QXcbAtom::_MOTIF_WM_HINTS),
+                            atom(QXcbAtom::_MOTIF_WM_HINTS),
+                            32,
+                            5,
+                            &mwmhints);
+    } else {
+        xcb_delete_property(xcb_connection(), m_window, atom(QXcbAtom::_MOTIF_WM_HINTS));
+    }
 }
 
 void QXcbWindow::changeNetWmState(bool set, xcb_atom_t one, xcb_atom_t two)
@@ -1225,62 +1181,6 @@ void QXcbWindow::setWindowState(Qt::WindowStates state)
     m_windowState = state;
 }
 
-void QXcbWindow::updateMotifWmHintsBeforeMap()
-{
-    QtMotifWmHints mwmhints = getMotifWmHints(connection(), m_window);
-
-    if (window()->modality() != Qt::NonModal) {
-        switch (window()->modality()) {
-        case Qt::WindowModal:
-            mwmhints.input_mode = MWM_INPUT_PRIMARY_APPLICATION_MODAL;
-            break;
-        case Qt::ApplicationModal:
-        default:
-            mwmhints.input_mode = MWM_INPUT_FULL_APPLICATION_MODAL;
-            break;
-        }
-        mwmhints.flags |= MWM_HINTS_INPUT_MODE;
-    } else {
-        mwmhints.input_mode = MWM_INPUT_MODELESS;
-        mwmhints.flags &= ~MWM_HINTS_INPUT_MODE;
-    }
-
-    if (windowMinimumSize() == windowMaximumSize()) {
-        // fixed size, remove the resize handle (since mwm/dtwm
-        // isn't smart enough to do it itself)
-        mwmhints.flags |= MWM_HINTS_FUNCTIONS;
-        if (mwmhints.functions == MWM_FUNC_ALL) {
-            mwmhints.functions = MWM_FUNC_MOVE;
-        } else {
-            mwmhints.functions &= ~MWM_FUNC_RESIZE;
-        }
-
-        if (mwmhints.decorations == MWM_DECOR_ALL) {
-            mwmhints.flags |= MWM_HINTS_DECORATIONS;
-            mwmhints.decorations = (MWM_DECOR_BORDER
-                                    | MWM_DECOR_TITLE
-                                    | MWM_DECOR_MENU);
-        } else {
-            mwmhints.decorations &= ~MWM_DECOR_RESIZEH;
-        }
-    }
-
-    if (window()->flags() & Qt::WindowMinimizeButtonHint) {
-        mwmhints.flags |= MWM_HINTS_DECORATIONS;
-        mwmhints.decorations |= MWM_DECOR_MINIMIZE;
-        mwmhints.functions |= MWM_FUNC_MINIMIZE;
-    }
-    if (window()->flags() & Qt::WindowMaximizeButtonHint) {
-        mwmhints.flags |= MWM_HINTS_DECORATIONS;
-        mwmhints.decorations |= MWM_DECOR_MAXIMIZE;
-        mwmhints.functions |= MWM_FUNC_MAXIMIZE;
-    }
-    if (window()->flags() & Qt::WindowCloseButtonHint)
-        mwmhints.functions |= MWM_FUNC_CLOSE;
-
-    setMotifWmHints(connection(), m_window, mwmhints);
-}
-
 void QXcbWindow::updateNetWmStateBeforeMap()
 {
     NetWmStates states(0);
diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index f7d76ed3b2..6667f45343 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -199,10 +199,9 @@ protected:
     NetWmStates netWmStates();
     void setNetWmStates(NetWmStates);
 
-    void setMotifWindowFlags(Qt::WindowFlags flags);
-    void setNetWmStateWindowFlags(Qt::WindowFlags flags);
+    void setMotifWmHints(Qt::WindowFlags flags);
 
-    void updateMotifWmHintsBeforeMap();
+    void setNetWmStateWindowFlags(Qt::WindowFlags flags);
     void updateNetWmStateBeforeMap();
 
     void setTransparentForMouseEvents(bool transparent);