Incubates #7997

source/NVDAObjects/UIA/__init__.py

@@ -268,7 +268,12 @@ def _getFormatFieldAtRange(self,textRange,formatConfig,ignoreMixedValues=False):
 	def __init__(self,obj,position,_rangeObj=None):
 		super(UIATextInfo,self).__init__(obj,position)
 		if _rangeObj:
-			self._rangeObj=_rangeObj.clone()
+			try:
+				self._rangeObj=_rangeObj.clone()
+			except COMError:
+				# IUIAutomationTextRange::clone can sometimes fail, such as in UWP account login screens
+				log.debugWarning("Could not clone range",exc_info=True)
+				raise RuntimeError("Could not clone range")
 		elif position in (textInfos.POSITION_CARET,textInfos.POSITION_SELECTION):
 			try:
 				sel=self.obj.UIATextPattern.GetSelection()

source/NVDAObjects/UIA/edge.py

@@ -572,6 +572,19 @@ def shouldPassThrough(self,obj,reason=None):
 			return True
 		return super(EdgeHTMLTreeInterceptor,self).shouldPassThrough(obj,reason=reason)
 
+	def makeTextInfo(self,position):
+		try:
+			return super(EdgeHTMLTreeInterceptor,self).makeTextInfo(position)
+		except RuntimeError as e:
+			# sometimes the stored TextRange we have for the caret/selection can die if the page mutates too much.
+			# Therefore, if we detect this, just give back the first position in the document, updating our stored version as we go.
+			if position in (textInfos.POSITION_SELECTION,textInfos.POSITION_CARET):
+				log.debugWarning("%s died. Using first position instead."%position)
+				info=self.makeTextInfo(textInfos.POSITION_FIRST)
+				self._selection=info
+				return info
+			raise e
+
 class EdgeHTMLRoot(EdgeNode):
 
 	treeInterceptorClass=EdgeHTMLTreeInterceptor

source/UIABrowseMode.py

@@ -336,6 +336,9 @@ def _get_UIAElementAtStart(self):
 class UIABrowseModeDocument(UIADocumentWithTableNavigation,browseMode.BrowseModeDocumentTreeInterceptor):
 
 	TextInfo=UIABrowseModeDocumentTextInfo
+	# UIA browseMode documents cannot remember caret positions across loads (I.e. when going back a page in Edge) 
+	# Because UIA TextRanges are opaque and are tied specifically to one particular document.
+	shouldRememberCaretPositionAcrossLoads=False
 
 	def _iterNodesByType(self,nodeType,direction="next",pos=None):
 		if nodeType.startswith("heading"):