### 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
ClassDB::bind_method(D_METHOD("get_next"), &TreeItem::get_next);
	ClassDB::bind_method(D_METHOD("get_prev"), &TreeItem::get_prev);
	ClassDB::bind_method(D_METHOD("get_parent"), &TreeItem::get_parent);
	ClassDB::bind_method(D_METHOD("get_first_child"), &TreeItem::get_first_child);
	ClassDB::bind_method(D_METHOD("get_next_visible", "wrap"), &TreeItem::get_next_visible, DEFVAL(false));
	ClassDB::bind_method(D_METHOD("get_prev_visible", "wrap"), &TreeItem::get_prev_visible, DEFVAL(false));
	ClassDB::bind_method(D_METHOD("get_child", "idx"), &TreeItem::get_child);
	ClassDB::bind_method(D_METHOD("get_child_count"), &TreeItem::get_child_count);
	ClassDB::bind_method(D_METHOD("get_children"), &TreeItem::get_children);
	ClassDB::bind_method(D_METHOD("get_index"), &TreeItem::get_index);
	ClassDB::bind_method(D_METHOD("move_before", "item"), &TreeItem::move_before);
	ClassDB::bind_method(D_METHOD("move_after", "item"), &TreeItem::move_after);
	ClassDB::bind_method(D_METHOD("remove_child", "child"), &TreeItem::remove_child);
	{
		MethodInfo mi;
		mi.name = "call_recursive";
		mi.arguments.push_back(PropertyInfo(Variant::STRING_NAME, "method"));
		ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, "call_recursive", &TreeItem::_call_recursive_bind, mi);
	}
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "collapsed"), "set_collapsed", "is_collapsed");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "visible"), "set_visible", "is_visible");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "disable_folding"), "set_disable_folding", "is_folding_disabled");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "custom_minimum_height", PROPERTY_HINT_RANGE, "0,1000,1"), "set_custom_minimum_height", "get_custom_minimum_height");
	BIND_ENUM_CONSTANT(CELL_MODE_STRING);
	BIND_ENUM_CONSTANT(CELL_MODE_CHECK);
	BIND_ENUM_CONSTANT(CELL_MODE_RANGE);
	BIND_ENUM_CONSTANT(CELL_MODE_ICON);
	BIND_ENUM_CONSTANT(CELL_MODE_CUSTOM);
}
void TreeItem::clear_children() {