Fixed multi-arg appends.
diff --git a/Mac/Tools/IDE/Wbase.py b/Mac/Tools/IDE/Wbase.py
index 46a8c96..e1e71b2 100644
--- a/Mac/Tools/IDE/Wbase.py
+++ b/Mac/Tools/IDE/Wbase.py
@@ -490,7 +490,7 @@
 		for panesize in panesizes:
 			if current:
 				self._gutters.append(current)
-			self._panesizes.append(current, current + panesize)
+			self._panesizes.append((current, current + panesize))
 			current = current + panesize
 		self.makepanebounds()