It would be quite useful if there was a means to increase the size of the preview panes letter preview other than drag resizing the window. On a laptop there isn’t really much vertical space to size the preview pane up without losing the edit window.
This is especially an issue when working using interpolated multiple masters and testing at high zooms any curve issues. The text size control at the bottom right of the window somewhat unintuitively increases the size of the edit window, when it seems like it should affect the preview panes text size.
Splitting the preview pane and edit window vertically is almost helpful on a laptop, but again there needs to be manual preview size control and you also lose the ability to drag the preview panes contents left to right.