### 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
return pressed_button;
}
Rect2 Tree::get_item_rect(TreeItem *p_item, int p_column, int p_button) const {
	ERR_FAIL_NULL_V(p_item, Rect2());
	ERR_FAIL_COND_V(p_item->tree != this, Rect2());
	if (p_column != -1) {
		ERR_FAIL_INDEX_V(p_column, columns.size(), Rect2());
	}
	if (p_button != -1) {
		ERR_FAIL_COND_V(p_column == -1, Rect2()); 
		ERR_FAIL_INDEX_V(p_button, p_item->cells[p_column].buttons.size(), Rect2());
	}
	int ofs = get_item_offset(p_item);
	int height = compute_item_height(p_item);
	Rect2 r;
	r.position.y = ofs;
	r.size.height = height;
	if (p_column == -1) {
		r.position.x = 0;
		r.size.x = get_size().width;