### 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
for (int i = 0; i < columns.size(); i++) {
		if (p_from->is_selected(i)) {
			return true;
		}
	}
	TreeItem *child_item = p_from->get_first_child();
	while (child_item) {
		if (_is_branch_selected(child_item)) {
			return true;
		}
		child_item = child_item->get_next();
	}
	return false;
}
bool Tree::_is_sibling_branch_selected(TreeItem *p_from) const {
	TreeItem *sibling_item = p_from->get_next();
	while (sibling_item) {
		if (_is_branch_selected(sibling_item)) {
			return true;
		}
		sibling_item = sibling_item->get_next();
	}
	return false;
}
void Tree::select_single_item(TreeItem *p_selected, TreeItem *p_current, int p_col, TreeItem *p_prev, bool *r_in_range, bool p_force_deselect) {