### 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 (pos.x < w) {
					r_column = i;
					return p_item;
				}
				pos.x -= w;
			}
			return nullptr;
		} else {
			pos.y -= h;
		}
	} else {
		h = 0;
	}
	if (p_item->is_collapsed() || !p_item->is_visible()) {
		return nullptr; 
	}
	TreeItem *n = p_item->get_first_child();
	while (n) {
		int ch;
		TreeItem *r = _find_item_at_pos(n, pos, r_column, ch, section);
		pos.y -= ch;
		h += ch;
		if (r) {
			return r;
		}
		n = n->get_next();
	}
	return nullptr;
}
int Tree::get_column_at_position(const Point2 &p_pos) const {