### 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
const int cell_h = compute_item_height(selected_item) + theme_cache.v_separation;
		int screen_h = area_size.height - tbh;
		if (h_scroll->is_visible()) {
			screen_h -= h_scroll->get_combined_minimum_size().height;
		}
		if (cell_h > screen_h) { 
			v_scroll->set_value(y_offset);
		} else if (y_offset + cell_h > v_scroll->get_value() + screen_h) {
			v_scroll->call_deferred(SNAME("set_value"), y_offset - screen_h + cell_h);
		} else if (y_offset < v_scroll->get_value()) {
			v_scroll->set_value(y_offset);
		}
	}
	if (select_mode != SELECT_ROW) { 
		int x_offset = 0;
		for (int i = 0; i < selected_col; i++) {
			x_offset += get_column_width(i);
		}
		const int cell_w = get_column_width(selected_col);
		const int screen_w = area_size.width - v_scroll->get_combined_minimum_size().width;
		if (cell_w > screen_w) {
			h_scroll->set_value(x_offset);
		} else if (x_offset + cell_w > h_scroll->get_value() + screen_w) {
			h_scroll->call_deferred(SNAME("set_value"), x_offset - screen_w + cell_w);
		} else if (x_offset < h_scroll->get_value()) {
			h_scroll->set_value(x_offset);
		}
	}
}
int Tree::get_pressed_button() const {