### 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 (c->get_visible_child_count() > 0) {
					root_pos -= Point2i(theme_cache.arrow->get_width(), 0);
				}
				float line_width = theme_cache.relationship_line_width * Math::round(theme_cache.base_scale);
				float parent_line_width = theme_cache.parent_hl_line_width * Math::round(theme_cache.base_scale);
				float children_line_width = theme_cache.children_hl_line_width * Math::round(theme_cache.base_scale);
				Point2i parent_pos = Point2i(parent_ofs - theme_cache.arrow->get_width() / 2, p_pos.y + label_h / 2 + theme_cache.arrow->get_height() / 2) - theme_cache.offset + p_draw_ofs;
				int more_prev_ofs = 0;
				if (root_pos.y + line_width >= 0) {
					if (rtl) {
						root_pos.x = get_size().width - root_pos.x;
						parent_pos.x = get_size().width - parent_pos.x;
					}
					
					if (_is_branch_selected(c)) {
						
						if (htotal >= 0) {
							RenderingServer::get_singleton()->canvas_item_add_line(ci, root_pos, Point2i(parent_pos.x + Math::floor(parent_line_width / 2), root_pos.y), theme_cache.parent_hl_line_color, parent_line_width);
						}
						RenderingServer::get_singleton()->canvas_item_add_line(ci, Point2i(parent_pos.x, root_pos.y + Math::floor(parent_line_width / 2)), Point2i(parent_pos.x, prev_hl_ofs), theme_cache.parent_hl_line_color, parent_line_width);
						more_prev_ofs = theme_cache.parent_hl_line_margin;
						prev_hl_ofs = root_pos.y + Math::floor(parent_line_width / 2);
					} else if (p_item->is_selected(0)) {
						
						
						if (_is_sibling_branch_selected(c)) {
							if (htotal >= 0) {
								RenderingServer::get_singleton()->canvas_item_add_line(ci, root_pos, Point2i(parent_pos.x + Math::floor(parent_line_width / 2), root_pos.y), theme_cache.children_hl_line_color, children_line_width);
							}
							RenderingServer::get_singleton()->canvas_item_add_line(ci, Point2i(parent_pos.x, root_pos.y + Math::floor(parent_line_width / 2)), Point2i(parent_pos.x, prev_hl_ofs), theme_cache.parent_hl_line_color, parent_line_width);