### 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
draw_item_rect(p_item->cells.write[i], ir, col, icon_col, outline_size, font_outline_color);
					downarrow->draw(ci, arrow_pos);
				} break;
			}
			if (i == 0) {
				ofs = get_column_width(0);
			} else {
				ofs += w + bw;
			}
			if (select_mode == SELECT_MULTI && selected_item == p_item && selected_col == i) {
				if (is_layout_rtl()) {
					cell_rect.position.x = get_size().width - cell_rect.position.x - cell_rect.size.x;
				}
				if (has_focus()) {
					theme_cache.cursor->draw(ci, cell_rect);
				} else {
					theme_cache.cursor_unfocus->draw(ci, cell_rect);
				}
			}
		}
		if (!p_item->disable_folding && !hide_folding && p_item->first_child && p_item->get_visible_child_count() != 0) { 
			Ref<Texture2D> arrow;
			if (p_item->collapsed) {
				if (is_layout_rtl()) {
					arrow = theme_cache.arrow_collapsed_mirrored;
				} else {
					arrow = theme_cache.arrow_collapsed;
				}
			} else {
				arrow = theme_cache.arrow;