The ability to filter the vehicle list with two drop-downs at the bottom of the window was added in #997. Window attributes var_88A and var_88C are used to store the values of these drop-downs. These attributes however are also used for storing and restoring the size of the window when the window is maximised (by tapping on the resizing handle without dragging).

The result of this is:

1. When you maximise the window, the filter drop-downs lose their data, and
2. If you then use the filter drop-downs, un-maximising the window will no longer restore the previous size of the window.