It is very convenient to add multiple dimensions to a filter pane, rather than creating separate filter panes for each filter.
However, if you want your filters to always appear in 'collapsed' view, then must create a separate filter pane for each dimension, and manually size it to be only one 'square' tall, because Qlik automatically expands the filters to fill the available space. Additionally, if you manually size a multi-dimension filter pane to force it closed, if you move to a different window size or screen resolution, Qlik will helpfully open it back up again.
I propose a simple checkbox in the Appearance settings for filter panes to toggle between 'Expand filters to fill available space' and 'Keep filters collapsed at all times'. This will enable the convenience of using multi-dimensional filter panes, while also keeping the aesthetic of closed filter panes.