Sorry I was mistaken on the function to override, this is the good one:
UCLASS()
class UMyGameViewportClient : public UGameViewportClient
{
GENERATED_BODY()
public:
virtual TOptional<bool> QueryShowFocus(const EFocusCause InFocusCause) const override;
}
.cpp code:
TOptional<bool> UMyGameViewportClient::QueryShowFocus(const EFocusCause InFocusCause) const
{
return false;
}
With this, the dotted line will no longer appear.
Tell me if this works for you.