### 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
if (!root) {
		return nullptr;
	}
	while (true) {
		if (!p_item) {
			p_item = root;
		} else {
			if (p_item->first_child) {
				p_item = p_item->first_child;
			} else if (p_item->next) {
				p_item = p_item->next;
			} else {
				while (!p_item->next) {
					p_item = p_item->parent;
					if (p_item == nullptr) {
						return nullptr;
					}
				}
				p_item = p_item->next;
			}
		}
		for (int i = 0; i < columns.size(); i++) {
			if (p_item->cells[i].selected) {
				return p_item;
			}
		}
	}
	return nullptr;
}
int Tree::get_column_minimum_width(int p_column) const {