### 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
String s2 = c.text.get_slicec(',', i);
			popup_menu->add_item(s2.get_slicec(':', 0), s2.get_slicec(':', 1).is_empty() ? i : s2.get_slicec(':', 1).to_int());
		}
		popup_menu->set_size(Size2(rect.size.width, 0));
		popup_menu->set_position(get_screen_position() + rect.position + Point2i(0, rect.size.height));
		popup_menu->popup();
		popup_edited_item = s;
		popup_edited_item_col = col;
		return true;
	} else if (c.mode == TreeItem::CELL_MODE_STRING || c.mode == TreeItem::CELL_MODE_RANGE) {
		Rect2 popup_rect;
		int value_editor_height = c.mode == TreeItem::CELL_MODE_RANGE ? value_editor->get_minimum_size().height : 0;
		
		Vector2 ofs(0, Math::floor((MAX(text_editor->get_minimum_size().height, rect.size.height - value_editor_height) - rect.size.height) / 2));
		Point2i textedpos = get_screen_position() + rect.position - ofs;
		cache.text_editor_position = textedpos;
		popup_rect.position = textedpos;
		popup_rect.size = rect.size;
		
		popup_rect.position.x += c.get_icon_size().x;
		popup_rect.size.x -= c.get_icon_size().x;
		text_editor->clear();
		text_editor->set_text(c.mode == TreeItem::CELL_MODE_STRING ? c.text : String::num(c.val, Math::range_step_decimals(c.step)));
		text_editor->select_all();
		if (c.mode == TreeItem::CELL_MODE_RANGE) {
			popup_rect.size.y += value_editor_height;
			value_editor->show();
			updating_value_editor = true;
			value_editor->set_min(c.min);
			value_editor->set_max(c.max);