Prevent touch controls from fading away while being held.

Fixes #20531

UI/TouchControlLayoutScreen.cpp

@@ -49,9 +49,10 @@ public:
 		scale_ = theScale_;
 	}
 
-	bool IsDown() override {
+	bool IsDown() const override {
 		// Don't want the button to enlarge and throw the user's perspective
-		// of button size off whack.
+		// of button size off whack. Also, the other purpose of IsDown is to prevent auto-hide,
+		// but it's not relevant here.
 		return false;
 	};