For non-WWT_MATRIX widgets, scrollbars need to take account of the internal padding used for the widget.
This is not normally noticeable as framerect padding is only 2 extra pixels
After sorting and filter lists for GUI, we often shirnk them to reduce size. However this has very little benefit:
1) The memory has already been allocated, so it doesn't prevent that memory being required.
2) It causes a new allocation and copy when the vector is shrunk, actually using more memory.
3) The list is in window state, so the lifetime is only while the window is open.
4) When a filter is clearer, the original size will be needed again, which will cause another allocation.
In fact it is beneficial to reserve to the known maximum in most cases, so do that instead.
GUIList has a pointer only to the start of each sort/filter func list, which has the potential for UB as it is unable to validate that the selected sort or filter type is in range.
Use a std::span instead and check if the selected type is in range before using it.
SetStringParameters() was called during widget tree init in the constructor.
Calls within a constructor cannot call the derived classes methods. This would result in invalid data being passed to the string system, which could then crash.
Having two ways (`FillNestedArray` and `SetupSmallestSize`) to initialize
`Window::nested_array` introduces confusion.
Instead, make `FillNestedArray` the canonical way, always call it, and remove
init_array from `SetupSmallestSize`.
When clicked, the button is still highlighted to show that it is active.
The bevel is controlled with widget_data by RWV_SHOW_BEVEL or RWV_HIDE_BEVEL values.
AssignSizePosition is used with negative values when an NWidgetMatrix is
scrolled, but they were passed as unsigned and then stored as signed.
Widget pos_x/pos_y were already made signed.
This simplifies processing nwidget parts as, unlike the remaining length, the pointer to the end of the list never changes. This is the same principle as we use(d) for tracking end instead of length for C-style strings.
And this removes 160~ instances of the lengthof() macro.
Having to choose between DropDownListStringItem, DropDownListCharStringItem, and DropDownListParamStringItem depending on whether to draw a StringID, a raw string, or a StringID with extra parameters was needlessly complex.
Instead, allow passing a StringID or raw string to DropDownListStringItem. This will preformat the StringID into a raw string, and can therefore accept parameters via the normal SetDParam mechanism.
This also means that strings no longer need to be formatted on every draw.
