feat: add solidify option to fast menu for non-manifold meshes

interface/fast_menu.py

@@ -153,6 +153,7 @@ def draw_single_object_predictions(self, context):
             self.sketch = len(self.faces) >= 1 and is_planar(bm)
             self.profile = len(self.faces) == 0 and len(self.edges) > 0
             self.form = len(self.faces) > 1
+            self.manifold = all([len(edge.link_faces) == 2 for edge in self.edges])
 
             bm.free()
 
@@ -181,7 +182,7 @@ def draw_single_object_predictions(self, context):
                 layout.operator("nd.cycle", icon=icons['nd.cycle'])
                 layout.separator()
 
-            if has_mod_solidify:
+            if not self.manifold or has_mod_solidify:
                 layout.operator("nd.solidify", icon=icons['nd.solidify'])
 
             if has_mod_profile_extrude: