### 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
ERR_FAIL_INDEX_V(p_column, cells.size(), "");
	return cells[p_column].suffix;
}
void TreeItem::set_icon(int p_column, const Ref<Texture2D> &p_icon) {
	ERR_FAIL_INDEX(p_column, cells.size());
	if (cells[p_column].icon == p_icon) {
		return;
	}
	cells.write[p_column].icon = p_icon;
	cells.write[p_column].cached_minimum_size_dirty = true;
	_changed_notify(p_column);
}
Ref<Texture2D> TreeItem::get_icon(int p_column) const {
	ERR_FAIL_INDEX_V(p_column, cells.size(), Ref<Texture2D>());
	return cells[p_column].icon;
}
void TreeItem::set_icon_region(int p_column, const Rect2 &p_icon_region) {
	ERR_FAIL_INDEX(p_column, cells.size());
	if (cells[p_column].icon_region == p_icon_region) {
		return;
	}
	cells.write[p_column].icon_region = p_icon_region;
	cells.write[p_column].cached_minimum_size_dirty = true;
	_changed_notify(p_column);
}
Rect2 TreeItem::get_icon_region(int p_column) const {