diff --git a/Orange/widgets/visualize/utils/widget.py b/Orange/widgets/visualize/utils/widget.py
index e71cbfe6855..4c8fbda1315 100644
--- a/Orange/widgets/visualize/utils/widget.py
+++ b/Orange/widgets/visualize/utils/widget.py
@@ -51,10 +51,10 @@ class OWProjectionWidgetBase(OWWidget, openclass=True):
     and a bool `np.ndarray` with indicators of valid (that is, shown)
     data points.
     """
-    attr_color = ContextSetting(None, required=ContextSetting.OPTIONAL)
-    attr_label = ContextSetting(None, required=ContextSetting.OPTIONAL)
-    attr_shape = ContextSetting(None, required=ContextSetting.OPTIONAL)
-    attr_size = ContextSetting(None, required=ContextSetting.OPTIONAL)
+    attr_color: Variable = ContextSetting(None, required=ContextSetting.OPTIONAL)
+    attr_label: Variable = ContextSetting(None, required=ContextSetting.OPTIONAL)
+    attr_shape: Variable = ContextSetting(None, required=ContextSetting.OPTIONAL)
+    attr_size: Variable = ContextSetting(None, required=ContextSetting.OPTIONAL)
 
     class Information(OWWidget.Information):
         missing_size = Msg(
@@ -378,7 +378,7 @@ class Warning(OWProjectionWidgetBase.Warning):
             "No subset data instances appear in input data")
 
     settingsHandler = DomainContextHandler()
-    selection = Setting(None, schema_only=True)
+    selection: list = Setting(None, schema_only=True)
     auto_commit = Setting(True)
 
     GRAPH_CLASS = OWScatterPlotBase