### Godot version

4.0 beta 10

### System information

Windows 11 Vulkan

### Issue description

Looked through the issues list, but couldn't find something like this, sorry in advance if this has already been reported.

There is a few cases (in the pictures below) where list of Actions in Input Map may not always show a scrollbar even if the actions list overflows (I imagine this could also happen for the widget that Input Map uses).

![image](https://user-images.githubusercontent.com/39958198/210003566-cf60dbaf-921f-485b-b0a9-51ffc28d0244.png)

![New Bitmap image](https://user-images.githubusercontent.com/39958198/210004079-8eb2e6a1-0cf5-4a7c-8905-a4e3cfd0ec5d.png)

![image](https://user-images.githubusercontent.com/39958198/210004165-a6b6790b-248a-4f68-b4d0-b44b25afdf4f.png)

![image](https://user-images.githubusercontent.com/39958198/210004537-aca52194-a464-48b9-b818-24782706de45.png)


### Steps to reproduce

The pictures are clearer than anything I could write here: "a picture is worth 1000 words"

### Minimal reproduction project

N/A
if (_scroll(false, mb->get_factor() / 8)) {
					accept_event();
				}
			} break;
			case MouseButton::WHEEL_LEFT: {
				if (_scroll(true, -mb->get_factor() / 8)) {
					accept_event();
				}
			} break;
			case MouseButton::WHEEL_RIGHT: {
				if (_scroll(true, mb->get_factor() / 8)) {
					accept_event();
				}
			} break;
			default:
				break;
		}
	}
	Ref<InputEventPanGesture> pan_gesture = p_event;
	if (pan_gesture.is_valid()) {
		double prev_v = v_scroll->get_value();
		v_scroll->set_value(v_scroll->get_value() + v_scroll->get_page() * pan_gesture->get_delta().y / 8);
		double prev_h = h_scroll->get_value();
		if (is_layout_rtl()) {
			h_scroll->set_value(h_scroll->get_value() + h_scroll->get_page() * -pan_gesture->get_delta().x / 8);
		} else {
			h_scroll->set_value(h_scroll->get_value() + h_scroll->get_page() * pan_gesture->get_delta().x / 8);
		}
		if (v_scroll->get_value() != prev_v || h_scroll->get_value() != prev_h) {
			accept_event();