Wow, cool tools! I have bookmarked the links to play some more! I also think that the simple tool in the pic in the OP would benefit from sliders to shift the boundaries between the panes.
Microsoft PowerToys is a set of utilities for customizing Windows. Utilities include ColorPicker, FancyZones, File Explorer Add-ons, Image Resizer, Keyboard Manager, PowerRename, PowerToys Run, a Shortcut Guide and more to come.