I have the following setup:
Primary monitor "A" 3840x2160, density 200%, giving effective 1920x1080
Secondary monitor "B" 1920x1080, density 100%, giving effective 1920x1080.
When WinSCP has a window completely on monitor B, the density for monitor A is used, resulting in large text (200% zoom) in the commander/explorer and editor. Other applications adjust their densities to match the monitor that contains at least 50% of the window, snapping the zoom if they are dragged or resized across monitors. The expected behavior is a 100% zoom when a window is bounded more than 50% within monitor B.
In display settings, monitor B is positioned to the right and slightly below monitor A (both monitors centered along the X axis).
When WinSCP is on monitor B and a new editor window is opened, the window seems to open relative to the bounds of monitor A, even though it correctly opens on monitor B. This often results in the top of the editor window opening outside the upper bounds of monitor B. If I try to move my mouse cursor to find the window top, the mouse cursor is correctly bounded by monitor B. The expected behavior is for new windows that open on monitor B to open within the bounds of monitor B.