try parent instead of sibling method

source/gui/__init__.py

@@ -715,7 +715,6 @@ def __init__(self, parent):
 		super(WelcomeDialog, self).__init__(parent, wx.ID_ANY, _("Welcome to NVDA"))
 
 		mainSizer=wx.BoxSizer(wx.VERTICAL)
-		mainSizerHelper = guiHelper.BoxSizerHelper(self, sizer=mainSizer)
 		# Translators: The header for the Welcome dialog when user starts NVDA for the first time. This is in larger,
 		# bold lettering 
 		welcomeTextHeader = wx.StaticText(self, label=_("Welcome to NVDA!"))
@@ -808,7 +807,7 @@ def __init__(self, parent):
 		# Translators: The label of the license text which will be shown when NVDA installation program starts.
 		groupLabel = _("License Agreement")
 		sizer = guiHelper.LTRStaticBoxSizer(wx.VERTICAL, self, label=groupLabel)
-		sHelper.addItem(sizer.GetStaticBox())
+		sHelper.addItem(sizer)
 		licenseTextCtrl = wx.TextCtrl(self, size=(500, 400), style=wx.TE_MULTILINE | wx.TE_READONLY | wx.TE_RICH)
 		licenseTextCtrl.Value = codecs.open(getDocFilePath("copying.txt", False), "r", encoding="UTF-8").read()
 		sizer.Add(licenseTextCtrl)

source/gui/guiHelper.py

@@ -324,7 +324,10 @@ def addLabeledControl(self, labelText, wxCtrlClass, **kwargs):
 			Relies on guiHelper.LabeledControlHelper and thus guiHelper.associateElements, and therefore inherits any
 			limitations from there.
 		"""
-		labeledControl = LabeledControlHelper(self.sizer.GetStaticBox(), labelText, wxCtrlClass, **kwargs)
+		parent = self._parent
+		if isinstance(self.sizer, wx.StaticBoxSizer):
+			parent = self.sizer.GetStaticBox()
+		labeledControl = LabeledControlHelper(parent, labelText, wxCtrlClass, **kwargs)
 		if(isinstance(labeledControl.control, (wx.ListCtrl,wx.ListBox,wx.TreeCtrl))):
 			self.addItem(labeledControl.sizer, flag=wx.EXPAND, proportion=1)
 		else:
@@ -345,6 +348,9 @@ def addDialogDismissButtons(self, buttons, separated=False):
 		  Should be set to L{False} for message or single input dialogs, L{True} otherwise.
 		@type separated: L{bool}
 		"""
+		parent = self._parent
+		if isinstance(self.sizer, wx.StaticBoxSizer):
+			parent = self.sizer.GetStaticBox()
 		if self.sizer.GetOrientation() != wx.VERTICAL:
 			raise NotImplementedError(
 				"Adding dialog dismiss buttons to a horizontal BoxSizerHelper is not implemented."
@@ -354,11 +360,11 @@ def addDialogDismissButtons(self, buttons, separated=False):
 		elif isinstance(buttons, (wx.Sizer, wx.Button)):
 			toAdd = buttons
 		elif isinstance(buttons, int):
-			toAdd = self.sizer.GetStaticBox().CreateButtonSizer(buttons)
+			toAdd = parent.CreateButtonSizer(buttons)
 		else:
 			raise NotImplementedError("Unknown type: {}".format(buttons))
 		if separated:
-			self.addItem(wx.StaticLine(self.sizer.GetStaticBox()), flag=wx.EXPAND)
+			self.addItem(wx.StaticLine(parent), flag=wx.EXPAND)
 		self.addItem(toAdd, flag=wx.ALIGN_RIGHT)
 		self.dialogDismissButtonsAdded = True
 		return buttons