MSHTML NVDAObject's event_caret: its posible for makeTextInfo positio…

…n_caret to raise RuntimeError if the object the event is for is not really the MSHTML selection (i.e. caret moves but the focus is not actually on the selected object). Just return early if this happens

source/NVDAObjects/IAccessible/MSHTML.py

@@ -311,8 +311,11 @@ def event_caret(self):
 		if self._ignoreCaretEvents: return
 		if self.TextInfo is not MSHTMLTextInfo:
 			return
-		newCaretBookmark=self.makeTextInfo(textInfos.POSITION_CARET).bookmark
-		if newCaretBookmark==getattr(self,'_oldCaretBookmark',None):
+		try:
+			newCaretBookmark=self.makeTextInfo(textInfos.POSITION_CARET).bookmark
+		except RuntimeError: #caret events can be fired on the object (focus) when  its not the real MSHTML selection 
+			newCaretBookmark=None
+		if not newCaretBookmark or newCaretBookmark==getattr(self,'_oldCaretBookmark',None):
 			return
 		self._oldCaretBookmark=newCaretBookmark
 		return super(MSHTML,self).event_caret()