Better EVT_MOTION handling in wxPGSpinButton

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57200 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/propgrid/advprops.cpp

@@ -194,8 +194,10 @@ private:
         {
             if ( m_bLeftDown )
             {
-                Capture();
                 int dy = m_ptPosition.y - event.GetPosition().y;
+                if ( dy )
+                {
+                    Capture();
                     m_ptPosition = event.GetPosition();
 
                     wxSpinEvent evtscroll( (dy >= 0) ? wxEVT_SCROLL_LINEUP :
@@ -203,11 +205,14 @@ private:
                                            GetId() );
                     evtscroll.SetEventObject(this);
 
+                    wxASSERT( m_spins == 1 );
+
                     m_spins = abs(dy);
                     GetEventHandler()->ProcessEvent(evtscroll);
                     m_spins = 1;
                 }
             }
+        }
 
         event.Skip();
     }