### 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 (root) {
		Point2 pos = p_pos;
		pos -= theme_cache.panel_style->get_offset();
		pos.y -= _get_title_button_height();
		if (pos.y < 0) {
			return -1;
		}
		if (h_scroll->is_visible_in_tree()) {
			pos.x += h_scroll->get_value();
		}
		if (v_scroll->is_visible_in_tree()) {
			pos.y += v_scroll->get_value();
		}
		int col, h, section;
		TreeItem *it = _find_item_at_pos(root, pos, col, h, section);
		if (it) {
			const TreeItem::Cell &c = it->cells[col];
			int col_width = get_column_width(col);
			for (int i = 0; i < col; i++) {
				pos.x -= get_column_width(i);
			}