### 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
}
			Point2 apos = p_pos + Point2i(0, (label_h - arrow->get_height()) / 2) - theme_cache.offset + p_draw_ofs;
			apos.x += theme_cache.item_margin - arrow->get_width();
			if (rtl) {
				apos.x = get_size().width - apos.x - arrow->get_width();
			}
			arrow->draw(ci, apos);
		}
	}
	Point2 children_pos = p_pos;
	if (!skip) {
		children_pos.x += theme_cache.item_margin;
		htotal += label_h;
		children_pos.y += htotal;
	}
	if (!p_item->collapsed) { 
		TreeItem *c = p_item->first_child;
		int base_ofs = children_pos.y - theme_cache.offset.y + p_draw_ofs.y;
		int prev_ofs = base_ofs;
		int prev_hl_ofs = base_ofs;
		while (c) {
			int child_h = -1;
			if (htotal >= 0) {
				child_h = draw_item(children_pos, p_draw_ofs, p_draw_size, c);
			}
			
			if (theme_cache.draw_relationship_lines > 0 && (!hide_root || c->parent != root) && c->is_visible()) {
				int root_ofs = children_pos.x + ((p_item->disable_folding || hide_folding) ? theme_cache.h_separation : theme_cache.item_margin);
				int parent_ofs = p_pos.x + theme_cache.item_margin;
				Point2i root_pos = Point2i(root_ofs, children_pos.y + label_h / 2) - theme_cache.offset + p_draw_ofs;