### 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
drag_speed = 0;
					drag_from = 0;
				}
				if (!click_handled) {
					drag_speed = 0;
					drag_accum = 0;
					
					drag_from = v_scroll->get_value();
					drag_touching = DisplayServer::get_singleton()->is_touchscreen_available();
					drag_touching_deaccel = false;
					if (drag_touching) {
						set_physics_process_internal(true);
					}
					if (mb->get_button_index() == MouseButton::LEFT) {
						if (get_item_at_position(mb->get_position()) == nullptr && !mb->is_shift_pressed() && !mb->is_ctrl_pressed() && !mb->is_command_or_control_pressed()) {
							emit_signal(SNAME("nothing_selected"));
						}
					}
				}
				if (propagate_mouse_activated) {
					emit_signal(SNAME("item_activated"));
					propagate_mouse_activated = false;
				}
			} break;
			case MouseButton::WHEEL_UP: {
				if (_scroll(false, -mb->get_factor() / 8)) {
					accept_event();
				}
			} break;
			case MouseButton::WHEEL_DOWN: {