Unreal Engine 4 UE4 Hack to bind a delegate to all key presses. This allows for multiple keys to be pressed down at once without blocking events.

bind-all-keys.cpp

// example.h
DECLARE_DYNAMIC_DELEGATE_TwoParams(FBindAllKeysDelegate, const FKey&, Key, bool, bKeyPressed);

// example.cpp
void UExampleStatics::BindAllKeyInputActions(AActor *Actor, const FBindAllKeysDelegate& Delegate)
{
  // Get input component from actor
	UInputComponent *InputComponent = Actor->InputComponent;
	if (InputComponent == nullptr) return;

  // Bind to all keys
	const FKey Key = EKeys::AnyKey;

  // Listen for key pressed
	FInputKeyBinding KBP(FInputChord(Key, false, false, false, false), EInputEvent::IE_Pressed);
	KBP.bConsumeInput = true;
	KBP.bExecuteWhenPaused = false;
	KBP.KeyDelegate.GetDelegateWithKeyForManualSet().BindLambda([=](const FKey& Key) {
		Delegate.ExecuteIfBound(Key, true);
	});
	InputComponent->KeyBindings.Add(KBP);

  // Listen for key released
	FInputKeyBinding KBR(FInputChord(Key, false, false, false, false), EInputEvent::IE_Released);
	KBR.bConsumeInput = true;
	KBR.bExecuteWhenPaused = false;
	KBR.KeyDelegate.GetDelegateWithKeyForManualSet().BindLambda([=](const FKey& Key) {
		Delegate.ExecuteIfBound(Key, false);
	});
	InputComponent->KeyBindings.Add(KBR);
}