overlay: Ensure overlay is properly positioned on show event

Author: ales-erjavec

Orange/widgets/utils/overlay.py

@@ -2,7 +2,7 @@
 Overlay Message Widget
 ----------------------
 
-A Widget to display a temporary dismissable message over another widget.
+A Widget to display a temporary dismissible message over another widget.
 
 """
 
@@ -102,6 +102,11 @@ def paintEvent(self, event):
         painter = QPainter(self)
         self.style().drawPrimitive(QStyle.PE_Widget, opt, painter, self)
 
+    def showEvent(self, event):
+        super().showEvent(event)
+        # Force immediate re-layout on show
+        self.__layout()
+
     def __layout(self):
         # position itself over `widget`
         # pylint: disable=too-many-branches
@@ -469,7 +474,7 @@ def buttonRole(self, button):
         """
         Return the ButtonRole for button
 
-        :type button: QAbsstractButton
+        :type button: QAbstractButton
         """
         for slot in self.__buttons:
             if slot.button is button: