NVDAObjects/UIA: forcefully raise value change event for combo boxes …

…that does expose value pattern yet does not raise the said event. re #6337 (#7132)

Some combo boxes do expose value pattern but do not raise value change event. To get around this, selection on its children (items) will be tracked (same trick as combo boxes with no value pattern).

* NVDAObjects/UIA: catch AttributeError seen in some lists. re #6337.

Caught by Jamie Teh (NV Access): when searching for items in store, the media type list is sometimes shown, and this may not have the required pattern at all. If this happens, Attribute Error is raised. When handling this, catch this error first, otherwise AttributeError will continue to be raised.

source/NVDAObjects/UIA/__init__.py

@@ -2,7 +2,7 @@
 #A part of NonVisual Desktop Access (NVDA)
 #This file is covered by the GNU General Public License.
 #See the file COPYING for more details.
-#Copyright (C) 2009-2016 NV Access Limited, Joseph Lee, Mohammad Suliman
+#Copyright (C) 2009-2017 NV Access Limited, Joseph Lee, Mohammad Suliman
 
 from ctypes import byref
 from ctypes.wintypes import POINT, RECT
@@ -1393,7 +1393,7 @@ def _get_UIASelectionPattern(self):
 	def _get_value(self):
 		try:
 			return self.UIASelectionPattern.GetCurrentSelection().GetElement(0).CurrentName
-		except COMError:
+		except (COMError, AttributeError):
 			return None
 
 class ListItem(UIA):
@@ -1402,8 +1402,9 @@ def event_stateChange(self):
 		if not self.hasFocus:
 			parent = self.parent
 			focus=api.getFocusObject()
-			if parent and isinstance(parent, ComboBoxWithoutValuePattern) and parent==focus: 
-				# This is an item in a combo box without the Value pattern.
+			if parent and parent==focus and (isinstance(parent, ComboBoxWithoutValuePattern)
+				or (parent._getUIACacheablePropertyValue(UIAHandler.UIA_IsValuePatternAvailablePropertyId) and parent.windowClassName.startswith("Windows.UI.Core"))):
+				# #6337: This is an item in a combo box without the Value pattern or does not raise value change event.
 				# This item has been selected, so notify the combo box that its value has changed.
 				focus.event_valueChange()
 		super(ListItem, self).event_stateChange()