diff --git a/harbour/ChangeLog b/harbour/ChangeLog
index cc0d591522..a2792287bb 100644
--- a/harbour/ChangeLog
+++ b/harbour/ChangeLog
@@ -17,6 +17,19 @@
    past entries belonging to author(s): Viktor Szakats.
 */
 
+2009-12-08 02:53 UTC+0100 Viktor Szakats (harbour.01 syenar.hu)
+  * contrib/hbqt/hbqt_slots.cpp
+    ! Fixed to check for NULL pointer and return error in
+      QT_CONNECT_EVENT() and QT_DISCONNECT_EVENT() and MyMainWindow desctructor.
+    ; TOFIX: Passing non-block to QT_MYMAINWINDOW() first parameter will cause GPFs.
+
+  * contrib/hbxbp/tests/demoxbp.prg
+  * contrib/hbxbp/xbpwindow.prg
+  * contrib/hbxbp/xbpdialog.prg
+  * contrib/hbxbp/xbpgeneric.prg
+    ! THREADID() -> HB_THREADID().
+      (former is not necessarily available in core)
+
 2009-12-08 02:41 UTC+0100 Viktor Szakats (harbour.01 syenar.hu)
   * contrib/hbqt/hbqt_slots.cpp
     % Eliminated local variable in all Slots:: method.
diff --git a/harbour/contrib/hbqt/hbqt_slots.cpp b/harbour/contrib/hbqt/hbqt_slots.cpp
index bcc78d7b88..7fc75e6a67 100644
--- a/harbour/contrib/hbqt/hbqt_slots.cpp
+++ b/harbour/contrib/hbqt/hbqt_slots.cpp
@@ -867,7 +867,7 @@ void Slots::paintRequested( QPrinter * printer )
  */
 HB_FUNC( QT_CONNECT_SIGNAL )
 {
-   QObject * object    = ( QObject * ) hbqt_gcpointer( 1 );         /* get sender    */
+   QObject * object = ( QObject * ) hbqt_gcpointer( 1 );         /* get sender    */
 
    if( object == NULL )
    {
@@ -1202,10 +1202,17 @@ HB_FUNC( QT_QEVENTFILTER )
 
 HB_FUNC( QT_CONNECT_EVENT )
 {
+   QObject * object = ( QObject* ) hbqt_gcpointer( 1 );          /* get sender    */
+
+   if( object == NULL )
+   {
+      hb_retl( HB_FALSE );
+      return;
+   }
+
    int       type      = hb_parni( 2 );
    PHB_ITEM  codeblock = hb_itemNew( hb_param( 3, HB_IT_BLOCK | HB_IT_BYREF ) );
    Events  * s_e       = qt_getEventFilter();
-   QObject * object    = ( QObject* ) hbqt_gcpointer( 1 );          /* get sender    */
 
    char prop[ 20 ];
    hb_snprintf( prop, sizeof( prop ), "%s%i%s", "P", type, "P" );    /* Make it a unique identifier */
@@ -1220,10 +1227,17 @@ HB_FUNC( QT_CONNECT_EVENT )
 
 HB_FUNC( QT_DISCONNECT_EVENT )
 {
+   QObject * object = ( QObject* ) hbqt_gcpointer( 1 );
+
+   if( object == NULL )
+   {
+      hb_retl( HB_FALSE );
+      return;
+   }
+
    int       type   = hb_parni( 2 );
    bool      bRet   = false;
    Events  * s_e    = qt_getEventFilter();
-   QObject * object = ( QObject* ) hbqt_gcpointer( 1 );
 
    char prop[ 10 ];
    hb_snprintf( prop, sizeof( prop ), "%s%i%s", "P", type, "P" );    /* Make it a unique identifier */
@@ -1268,7 +1282,8 @@ MyMainWindow::~MyMainWindow( void )
 #if defined( __HB_DEBUG__ )
 hbqt_debug( "               MyMainWindow::~MyMainWindow 0" );
 #endif
-   hb_itemRelease( block );
+   if( block )
+      hb_itemRelease( block );
 #if defined( __HB_DEBUG__ )
 hbqt_debug( "               MyMainWindow::~MyMainWindow 1" );
 #endif
diff --git a/harbour/contrib/hbxbp/tests/demoxbp.prg b/harbour/contrib/hbxbp/tests/demoxbp.prg
index 297b86135e..6a16c5a70c 100644
--- a/harbour/contrib/hbxbp/tests/demoxbp.prg
+++ b/harbour/contrib/hbxbp/tests/demoxbp.prg
@@ -115,7 +115,7 @@ FUNCTION _BuildADialog()
 PROCEDURE DispMem( cMessage )
 
    HB_SYMBOL_UNUSED( cMessage )
-   HBXBP_DEBUG( ThreadID(), padc( cMessage, 40 ), memory( 1001 ), hbqt_getMemUsed() )
+   HBXBP_DEBUG( hb_threadId(), padc( cMessage, 40 ), memory( 1001 ), hbqt_getMemUsed() )
 
    RETURN
 
@@ -123,7 +123,7 @@ PROCEDURE DispMem( cMessage )
 
 PROCEDURE BuildADialog()
    LOCAL oDlg, mp1, mp2, oXbp, nEvent, aSize, oDa, aTabs, oHTM
-   LOCAL nThread := ThreadID()
+   LOCAL nThread := hb_threadId()
    //LOCAL oStat, aMenu, aTool, aBrow, aChek, a3Sta
 
 HBXBP_DEBUG( "  .   " )
@@ -1985,4 +1985,3 @@ STATIC FUNCTION TBPrev()
    RETURN lMoved
 
 /*----------------------------------------------------------------------*/
-
diff --git a/harbour/contrib/hbxbp/xbpdialog.prg b/harbour/contrib/hbxbp/xbpdialog.prg
index bb9982067d..2ca5093c0f 100644
--- a/harbour/contrib/hbxbp/xbpdialog.prg
+++ b/harbour/contrib/hbxbp/xbpdialog.prg
@@ -120,13 +120,13 @@ METHOD XbpDialog:create( oParent, oOwner, aPos, aSize, aPresParams, lVisible )
 
    ::xbpWindow:create( oParent, oOwner, aPos, aSize, aPresParams, lVisible )
 
-   ::cargo := ThreadID()                               /* To Be Removed */
+   ::cargo := hb_threadId()                               /* To Be Removed */
 
    #ifdef __QMAINWINDOW__
    ::oWidget := QMainWindow():new()
    //::oWidget:setMouseTracking( .t. )
    #else
-   ::oWidget := QMainWindow():configure( QT_MyMainWindow( {|n,p| ::grabEvent( n,p ) }, ThreadID() ) )
+   ::oWidget := QMainWindow():configure( QT_MyMainWindow( {|n,p| ::grabEvent( n,p ) }, hb_threadId() ) )
    #endif
 
    IF !empty( ::title )
@@ -306,4 +306,3 @@ METHOD XbpDrawingArea:create( oParent, oOwner, aPos, aSize, aPresParams, lVisibl
    RETURN Self
 
 /*----------------------------------------------------------------------*/
-
diff --git a/harbour/contrib/hbxbp/xbpgeneric.prg b/harbour/contrib/hbxbp/xbpgeneric.prg
index 68f2d3b46f..1b04eb1ef7 100644
--- a/harbour/contrib/hbxbp/xbpgeneric.prg
+++ b/harbour/contrib/hbxbp/xbpgeneric.prg
@@ -182,21 +182,21 @@ FUNCTION SetAppEvent( nEvent, mp1, mp2, oXbp )
       t_nEventIn := 1
    ENDIF
 
-//HBXBP_DEBUG( 0, "SetAppEvent ... ", threadID(), nEvent, xbeP_Paint )
+//HBXBP_DEBUG( 0, "SetAppEvent ... ", hb_threadId(), nEvent, xbeP_Paint )
 
    t_events[ t_nEventIn, 1 ] := nEvent
    t_events[ t_nEventIn, 2 ] := mp1
    t_events[ t_nEventIn, 3 ] := mp2
    t_events[ t_nEventIn, 4 ] := oXbp
 
-//HBXBP_DEBUG( 1, "SetAppEvent ... ", threadID(), nEvent )
+//HBXBP_DEBUG( 1, "SetAppEvent ... ", hb_threadId(), nEvent )
    RETURN nil
 
 /*----------------------------------------------------------------------*/
 
 FUNCTION AppEvent( mp1, mp2, oXbp, nTimeout )
    LOCAL nEvent
-   //LOCAL nThreadID := ThreadID()
+   //LOCAL nThreadID := hb_threadId()
 
    //DEFAULT nTimeout TO 0
    HB_SYMBOL_UNUSED( nTimeOut )
@@ -218,7 +218,7 @@ FUNCTION AppEvent( mp1, mp2, oXbp, nTimeout )
       ENDIF
       hb_releaseCPU()
    ENDDO
-//HBXBP_DEBUG( "..........................", threadID() )
+//HBXBP_DEBUG( "..........................", hb_threadId() )
 
    RETURN nEvent
 
diff --git a/harbour/contrib/hbxbp/xbpwindow.prg b/harbour/contrib/hbxbp/xbpwindow.prg
index bd45e26c81..c71dc7c758 100644
--- a/harbour/contrib/hbxbp/xbpwindow.prg
+++ b/harbour/contrib/hbxbp/xbpwindow.prg
@@ -451,7 +451,7 @@ METHOD XbpWindow:grabEvent( nEvent, pEvent, oXbp )
 
    HB_SYMBOL_UNUSED( oXbp )
 
-//HBXBP_DEBUG(  threadID(), "XbpWindow:grabEvent", nEvent )
+//HBXBP_DEBUG(  hb_threadId(), "XbpWindow:grabEvent", nEvent )
 
    SWITCH ( nEvent )
 
@@ -736,7 +736,7 @@ METHOD XbpWindow:destroy()
    LOCAL cXbp := __ObjGetClsName( self )
 
 //HBXBP_DEBUG( ".   " )
-//HBXBP_DEBUG( ThreadID(),"Destroy: "+pad(__ObjGetClsName( self ),12)+ IF(empty(::cargo),'',str(::cargo) ), memory( 1001 ), hbqt_getMemUsed() )
+//HBXBP_DEBUG( hb_threadId(),"Destroy: "+pad(__ObjGetClsName( self ),12)+ IF(empty(::cargo),'',str(::cargo) ), memory( 1001 ), hbqt_getMemUsed() )
 
    IF cXbp == "XBPDIALOG"
       SetEventLoop( NIL )
@@ -773,7 +773,7 @@ METHOD XbpWindow:destroy()
       ::oWidget := NIL
    ENDIF
 
-//HBXBP_DEBUG( ThreadID(),"          Destroy: "+pad(__ObjGetClsName( self ),12)+ IF(empty(::cargo),'',str(::cargo) ), memory( 1001 ), hbqt_getMemUsed() )
+//HBXBP_DEBUG( hb_threadId(),"          Destroy: "+pad(__ObjGetClsName( self ),12)+ IF(empty(::cargo),'',str(::cargo) ), memory( 1001 ), hbqt_getMemUsed() )
 
    RETURN NIL