Please paste the backtrace from the crash dialog

Created attachment 20088 [details]
backtrace

Not a good one since akregator was compiled without debug options...

This is a kdelibs problem with the hover icons and already reported I think. One needs to middle-click the icon and move the mouse then, leaving the mouse button pressed. Quite reproducible. If I just had my mouse near me... (Macbooks with one-button touchpads are a bad testing environment for that). However, this is a dupe of a bug that was rassigned to kdelibs a long time ago.

Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1245591888 (LWP 17395)]
[KCrash handler]
#6  0x00000000 in ?? ()
#7  0xb63c3b88 in QApplication::internalNotify ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#8  0xb63c59b7 in QApplication::notify ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#9  0xb6ac9c5e in KApplication::notify (this=0xbf85fde0, receiver=0x8d35848, 
    event=0xbf85f9ac) at kapplication.cpp:550
#10 0xb77209be in QApplication::sendEvent (receiver=0x8d35848, 
    event=0xbf85f9ac) at /usr/share/qt3/include/qapplication.h:520
#11 0xb63c42d8 in qt_dispatchEnterLeave ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#12 0xb63538a0 in QApplication::x11ProcessEvent ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#13 0xb636a320 in QEventLoop::processEvents ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#14 0xb63de25e in QEventLoop::enterLoop ()
   from /usr/share/qt3/lib/libqt-mt.so.3
#15 0xb63de06e in QEventLoop::exec () from /usr/share/qt3/lib/libqt-mt.so.3
#16 0xb63c5731 in QApplication::exec () from /usr/share/qt3/lib/libqt-mt.so.3
#17 0x0805174a in main (argc=134563144, argv=0xbf85ff74) at main.cpp:112

My personal guess is that the hover button is destroyed when the mouse leaves the button in middle click mode, and the Qt event handling doesn't like that.

That was it, will suggest the following patch to k-c-d later.

Index: ktabbar.cpp
===================================================================
--- ktabbar.cpp (revision 644948)
+++ ktabbar.cpp (working copy)
@@ -186,7 +186,8 @@
                     if ( mHoverCloseButtonTab == t )
                         return;
                     mEnableCloseButtonTimer->stop();
-                    delete mHoverCloseButton;
+                    mHoverCloseButton->deleteLater();
+                    mHoverCloseButton = 0;
                 }

                 mHoverCloseButton = new QPushButton( this );
@@ -206,7 +207,7 @@
         }
         if ( mHoverCloseButton ) {
             mEnableCloseButtonTimer->stop();
-            delete mHoverCloseButton;
+            mHoverCloseButton->deleteLater();
             mHoverCloseButton = 0;
         }
     }

SVN commit 646812 by osterfeld:

Do not crash when pressing MMB on the hover icon and moving the mouse leaving MMB pressed.

BUG: 143387


 M  +3 -2      ktabbar.cpp  


--- branches/KDE/3.5/kdelibs/kdeui/ktabbar.cpp #646811:646812
@@ -186,7 +186,8 @@
                     if ( mHoverCloseButtonTab == t )
                         return;
                     mEnableCloseButtonTimer->stop();
-                    delete mHoverCloseButton;
+                    mHoverCloseButton->deleteLater();
+                    mHoverCloseButton = 0;
                 }
 
                 mHoverCloseButton = new QPushButton( this );
@@ -206,7 +207,7 @@
         }
         if ( mHoverCloseButton ) {
             mEnableCloseButtonTimer->stop();
-            delete mHoverCloseButton;
+            mHoverCloseButton->deleteLater();
             mHoverCloseButton = 0;
         }
     }