move onClose binding to individual apps rather than core

fsl/gui/core.py

@@ -210,10 +210,6 @@ def layout(parent, buildSpec, propObj):
     return parent
 
 
-def onClose(event):
-    wx.GetApp().ExitMainLoop()
-
-
 def buildGUI(buildSpec, propObj):
     """
     build a GUI from a build spec dictionary (or JSON)
@@ -230,7 +226,6 @@ def buildGUI(buildSpec, propObj):
 
     mainWin.Centre()
     mainWin.Show()
-    mainWin.Bind(wx.EVT_CLOSE, onClose)
     return mainWin