### 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
TreeItem *c = p_item->first_child;
			while (c) {
				int child_h = propagate_mouse_event(new_pos, x_ofs, y_ofs, x_limit, p_double_click, c, p_button, p_mod);
				if (child_h < 0) {
					return -1; 
				}
				new_pos.y -= child_h;
				y_ofs += child_h;
				c = c->next;
				item_h += child_h;
			}
		}
		if (p_item == root) {
			emit_signal(SNAME("empty_clicked"), get_local_mouse_position(), p_button);
		}
	}
	return item_h; 
}
void Tree::_text_editor_modal_close() {
	if (Input::get_singleton()->is_key_pressed(Key::ESCAPE) ||
			Input::get_singleton()->is_key_pressed(Key::KP_ENTER) ||
			Input::get_singleton()->is_key_pressed(Key::ENTER)) {
		return;
	}
	if (value_editor->has_point(value_editor->get_local_mouse_position())) {
		return;
	}
	_text_editor_submit(text_editor->get_text());
}
void Tree::_text_editor_submit(String p_text) {