### 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
TreeItem *current = get_parent();
	if (!current) {
		return;
	}
	bool all_unchecked_and_not_indeterminate = true;
	bool any_unchecked_or_indeterminate = false;
	TreeItem *child_item = current->get_first_child();
	while (child_item) {
		if (!child_item->is_checked(p_column)) {
			any_unchecked_or_indeterminate = true;
			if (child_item->is_indeterminate(p_column)) {
				all_unchecked_and_not_indeterminate = false;
				break;
			}
		} else {
			all_unchecked_and_not_indeterminate = false;
		}
		child_item = child_item->get_next();
	}
	if (all_unchecked_and_not_indeterminate) {
		current->set_checked(p_column, false);
	} else if (any_unchecked_or_indeterminate) {
		current->set_indeterminate(p_column, true);
	} else {
		current->set_checked(p_column, true);
	}