### 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
ADD_SIGNAL(MethodInfo("item_edited"));
	ADD_SIGNAL(MethodInfo("custom_item_clicked", PropertyInfo(Variant::INT, "mouse_button_index")));
	ADD_SIGNAL(MethodInfo("item_custom_button_pressed"));
	ADD_SIGNAL(MethodInfo("item_double_clicked"));
	ADD_SIGNAL(MethodInfo("item_collapsed", PropertyInfo(Variant::OBJECT, "item", PROPERTY_HINT_RESOURCE_TYPE, "TreeItem")));
	ADD_SIGNAL(MethodInfo("check_propagated_to_item", PropertyInfo(Variant::OBJECT, "item", PROPERTY_HINT_RESOURCE_TYPE, "TreeItem"), PropertyInfo(Variant::INT, "column")));
	ADD_SIGNAL(MethodInfo("button_clicked", PropertyInfo(Variant::OBJECT, "item", PROPERTY_HINT_RESOURCE_TYPE, "TreeItem"), PropertyInfo(Variant::INT, "column"), PropertyInfo(Variant::INT, "id"), PropertyInfo(Variant::INT, "mouse_button_index")));
	ADD_SIGNAL(MethodInfo("custom_popup_edited", PropertyInfo(Variant::BOOL, "arrow_clicked")));
	ADD_SIGNAL(MethodInfo("item_activated"));
	ADD_SIGNAL(MethodInfo("column_title_clicked", PropertyInfo(Variant::INT, "column"), PropertyInfo(Variant::INT, "mouse_button_index")));
	ADD_SIGNAL(MethodInfo("nothing_selected"));
	BIND_ENUM_CONSTANT(SELECT_SINGLE);
	BIND_ENUM_CONSTANT(SELECT_ROW);
	BIND_ENUM_CONSTANT(SELECT_MULTI);
	BIND_ENUM_CONSTANT(DROP_MODE_DISABLED);
	BIND_ENUM_CONSTANT(DROP_MODE_ON_ITEM);
	BIND_ENUM_CONSTANT(DROP_MODE_INBETWEEN);
}
Tree::Tree() {
	columns.resize(1);
	set_focus_mode(FOCUS_ALL);
	popup_menu = memnew(PopupMenu);
	popup_menu->hide();
	add_child(popup_menu, false, INTERNAL_MODE_FRONT);
	popup_editor = memnew(Popup);
	add_child(popup_editor, false, INTERNAL_MODE_FRONT);
	popup_editor_vb = memnew(VBoxContainer);
	popup_editor->add_child(popup_editor_vb);
	popup_editor_vb->add_theme_constant_override("separation", 0);
	popup_editor_vb->set_anchors_and_offsets_preset(PRESET_FULL_RECT);