### 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
switch (p_what) {
		case NOTIFICATION_FOCUS_ENTER: {
			if (get_viewport()) {
				focus_in_id = get_viewport()->get_processed_events_count();
			}
		} break;
		case NOTIFICATION_MOUSE_EXIT: {
			if (cache.hover_type != Cache::CLICK_NONE) {
				cache.hover_type = Cache::CLICK_NONE;
				queue_redraw();
			}
		} break;
		case NOTIFICATION_VISIBILITY_CHANGED: {
			drag_touching = false;
		} break;
		case NOTIFICATION_DRAG_END: {
			drop_mode_flags = 0;
			scrolling = false;
			set_physics_process_internal(false);
			queue_redraw();
		} break;
		case NOTIFICATION_DRAG_BEGIN: {
			single_select_defer = nullptr;
			if (theme_cache.scroll_speed > 0) {
				scrolling = true;
				set_physics_process_internal(true);
			}
		} break;
		case NOTIFICATION_INTERNAL_PHYSICS_PROCESS: {