### 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
emit_signal(SNAME("item_mouse_selected"), get_local_mouse_position(), p_button);
					
				} else {
					p_item->deselect(col);
					emit_signal(SNAME("multi_selected"), p_item, col, false);
					
				}
			} else {
				if (c.selectable) {
					if (select_mode == SELECT_MULTI && p_mod->is_shift_pressed() && selected_item && selected_item != p_item) {
						bool inrange = false;
						select_single_item(p_item, root, col, selected_item, &inrange);
						emit_signal(SNAME("item_mouse_selected"), get_local_mouse_position(), p_button);
					} else {
						int icount = _count_selected_items(root);
						if (select_mode == SELECT_MULTI && icount > 1 && p_button != MouseButton::RIGHT) {
							single_select_defer = p_item;
							single_select_defer_column = col;
						} else {
							if (p_button != MouseButton::RIGHT || !c.selected) {
								select_single_item(p_item, root, col);
							}
							emit_signal(SNAME("item_mouse_selected"), get_local_mouse_position(), p_button);
						}
					}
					/*
					if (!c.selected && select_mode==SELECT_MULTI) {
						emit_signal(SNAME("multi_selected"),p_item,col,true);
					}
					*/