design: mouse can only select streamed elements

design/fresnel.register.pas

@@ -409,12 +409,25 @@ end;
 
 function TFresnelFormMediator.ComponentAtPos(p: TPoint;
   MinClass: TComponentClass; Flags: TDMCompAtPosFlags): TComponent;
+var
+  ElArr: TFresnelElementArray;
+  El: TFresnelElement;
+  i: Integer;
 begin
   if Flags=[] then ;
-  Result:=DsgnForm.GetElementAt(p.X,p.Y);
-  if Result=nil then exit;
-  if (MinClass<>nil) and not Result.InheritsFrom(MinClass) then
-    Result:=nil;
+  // skip sub elements aka return only elements owned by the lookup root,
+  // which are streamed
+  ElArr:=DsgnForm.GetElementsAt(p.X,p.Y);
+  for i:=0 to length(ElArr)-1 do
+  begin
+    El:=ElArr[i];
+    if (El=DsgnForm) or (El.Owner=DsgnForm) then
+    begin
+      if (MinClass=nil) or El.InheritsFrom(MinClass) then
+        exit(El);
+    end;
+  end;
+  Result:=nil;
 end;
 
 function TFresnelFormMediator.ParentAcceptsChild(Parent: TComponent;