-static void gtk_slider_callback( GtkWidget *WXUNUSED(widget), wxSlider *win )
-{ 
-  if (!win->HasVMT()) return;
-  if (g_blockEventsOnDrag) return;
-    
-  float diff = win->m_adjust->value - win->m_oldPos;
-  if (fabs(diff) < 0.2) return;
-  
-  wxEventType command = wxEVT_NULL;
-  
-  float line_step = win->m_adjust->step_increment;
-  float page_step = win->m_adjust->page_increment;
-  
-  if (fabs(win->m_adjust->value-win->m_adjust->lower) < 0.2) command = wxEVT_SCROLL_BOTTOM;
-  else if (fabs(win->m_adjust->value-win->m_adjust->upper) < 0.2) command = wxEVT_SCROLL_TOP;
-  else if (fabs(diff-line_step) < 0.2) command = wxEVT_SCROLL_LINEDOWN;
-  else if (fabs(diff+line_step) < 0.2) command = wxEVT_SCROLL_LINEUP;
-  else if (fabs(diff-page_step) < 0.2) command = wxEVT_SCROLL_PAGEDOWN;
-  else if (fabs(diff+page_step) < 0.2) command = wxEVT_SCROLL_PAGEUP;
-  else command = wxEVT_SCROLL_THUMBTRACK;
-
-  int value = (int)(win->m_adjust->value+0.5);
-      
-  int orient = wxHORIZONTAL;
-  if (win->GetWindowStyleFlag() & wxSB_VERTICAL == wxSB_VERTICAL) orient = wxVERTICAL;
-  
-  wxScrollEvent event( command, win->GetId(), value, orient );
-  event.SetEventObject( win );
-  win->ProcessEvent( event );
-  
-  wxCommandEvent cevent( wxEVT_COMMAND_SLIDER_UPDATED, win->GetId() );
-  cevent.SetEventObject( win );
-  win->ProcessEvent( cevent );
+static void gtk_slider_callback( GtkAdjustment *adjust,
+                                 SCROLLBAR_CBACK_ARG
+                                 wxSlider *win )
+{
+    if (g_isIdle) wxapp_install_idle_handler();
+
+    if (!win->m_hasVMT) return;
+    if (g_blockEventsOnDrag) return;
+
+    float diff = adjust->value - win->m_oldPos;
+    if (fabs(diff) < sensitivity) return;
+
+    win->m_oldPos = adjust->value;
+
+    wxEventType command = GtkScrollTypeToWx(GET_SCROLL_TYPE(win->m_widget));
+
+    double dvalue = adjust->value;
+    int value = (int)(dvalue < 0 ? dvalue - 0.5 : dvalue + 0.5);
+
+    int orient = win->GetWindowStyleFlag() & wxSL_VERTICAL ? wxVERTICAL
+                                                           : wxHORIZONTAL;
+
+    wxScrollEvent event( command, win->GetId(), value, orient );
+    event.SetEventObject( win );
+    win->GetEventHandler()->ProcessEvent( event );
+
+    wxCommandEvent cevent( wxEVT_COMMAND_SLIDER_UPDATED, win->GetId() );
+    cevent.SetEventObject( win );
+    cevent.SetInt( value );
+    win->GetEventHandler()->ProcessEvent( cevent );