qt-bugs@ issue :  none
Trolltech task ID : none
bugs.kde.org number :
applied: no
author: Dirk Mueller <mueller@kde.org>

only trust libxinerama if its not the emulated information
coming from xrandr 1.2. xrandr 1.2 is merged fb and libxinerama
presents then virtual screens in clone mode, which qt (and KDE)
can't deal with.

proper fix would be to detect crtcs as virtual screens, but
given that qt can't deal with dynamically changing number of screens,
this is for "when I have time".

also includes a race fix that can cause the whole KDE session to crash
when you resize the screen.

--- src/gui/kernel/qdesktopwidget_x11.cpp
+++ src/gui/kernel/qdesktopwidget_x11.cpp
@@ -122,13 +122,16 @@ void QDesktopWidgetPrivate::init()
     int unused;
     use_xinerama = (XineramaQueryExtension(X11->display, &unused, &unused) && XineramaIsActive(X11->display));
 
-    if (use_xinerama) {
+    if (use_xinerama)
         xinerama_screeninfo =
             XineramaQueryScreens(X11->display, &screenCount);
+
+    if (use_xinerama && xinerama_screeninfo) {
         defaultScreen = 0;
     } else
 #endif // QT_NO_XINERAMA
     {
+        use_xinerama = false;
         defaultScreen = DefaultScreen(X11->display);
         screenCount = ScreenCount(X11->display);
     }
@@ -139,8 +142,8 @@ void QDesktopWidgetPrivate::init()
     workareas = new QRect[screenCount];
 
     // get the geometry of each screen
-    int i, x, y, w, h;
-    for (i = 0; i < screenCount; i++) {
+    int i, j, x, y, w, h;
+    for (i = 0, j = 0; i < screenCount; i++, j++) {
 
 #ifndef QT_NO_XINERAMA
         if (use_xinerama) {
@@ -157,11 +160,21 @@ void QDesktopWidgetPrivate::init()
                 h = HeightOfScreen(ScreenOfDisplay(X11->display, i));
             }
 
-        rects[i].setRect(x, y, w, h);
+        rects[j].setRect(x, y, w, h);
+        if (j > 0 && rects[j-1].intersects(rects[j]) &&
+                (rects[j].width()*rects[j].height()) >
+                (rects[j-1].width()*rects[j-1].height())) {
+            rects[j-1] = rects[j];
+           j--;
+        }
         workareas[i] = QRect();
     }
+    screenCount = j;
 
 #ifndef QT_NO_XINERAMA
+    if (use_xinerama && screenCount == 1)
+        use_xinerama = false;
+
     if (xinerama_screeninfo)
         XFree(xinerama_screeninfo);
 #endif // QT_NO_XINERAMA