qtvcp : add panel instance reference, fix check for preference

lib/python/qtvcp/qt_makegui.py

@@ -222,7 +222,7 @@ def apply_styles(self, fname=None):
 
         # Check for Preference file specified qss
         if fname is None:
-            if self.PREFS_:
+            if not self.PREFS_ is None:
                 path = self.PREFS_.getpref('style_QSS_Path', 'DEFAULT', str, 'BOOK_KEEPING')
                 if path.lower() == 'none':
                     return

lib/python/qtvcp/qt_makepins.py

@@ -42,6 +42,7 @@ def __init__(self, halcomp, path, window, debug):
         xmlname = path.XML
         self.window = window
         self.window['PREFS_'] = None
+        self.window['panel_'] = self
         self._screenOptions = None
         self._geo_string = ''
 
@@ -121,7 +122,7 @@ def __init__(self, halcomp, path, window, debug):
     # Search all hal-ifed widgets for _hal_cleanup functions and call them
     # used for such things as preference recording current settings
     def shutdown(self):
-        if self.window['PREFS_']:
+        if not self.window['PREFS_'] is None:
             self.record_preference_geometry()
         LOG.debug("Calling widget's _hal_cleanup functions.")
         for widget in self.window.getRegisteredHalWidgetList():
@@ -153,7 +154,7 @@ def record_preference_geometry(self):
     # if there is a screen option widget and we haven't set INI switch geometry
     # then call screenoptions function to set preference geometry
     def set_preference_geometry(self):
-        if self.window['PREFS_']:
+        if not self.window['PREFS_'] is None:
             self.geometry_parsing()
         else:
             LOG.info('No preference file - cannot set preference geometry.')