Cool, I will try that and report how it goes. Thanks!
Edit:
Oops, didn’t see the data type in hurry. Do you mean to replace the
TSharedPtr<SScissorRectBox> ScissorRectBox = SNew(SScissorRectBox)[RebuildListWidget()];
with
FScissorRectSlot(SWidget* InOwner = nullptr)
?