SuperSize is currently in development.
SuperSize allows you to resize your windows across multiple displays with different and user-selectable logic.
It started out as a simple C# program that hooks into the Win32 API to resize windows across the entire screen, but I thought it would be fun to expand it into an entire program with a pluggable API to let you customise how the maximising played out.
For tinkerers, there will also be another plugin for scripting your own logic, the original implementation was based on IronPython, but may switch to another scripting language before release.
Download
Test builds are occasionally released on GitHub.
The final release will also be published on the Microsoft Store.
The Python plugin is not yet available.
Plugin API
The Plugin API will be published at some point soon once the plugin loader is more complete.
Example Python Script
primary = get_screens()[0].Bounds
center = point(primary.X + primary.Width / 2, primary.Height / 2)
all_bounds = get_all_screen_bounds()
d_top = abs(center.Y - all_bounds.Top)
d_right = abs(center.X - all_bounds.Right)
d_bottom = abs(center.Y - all_bounds.Bottom)
d_left = abs(center.X - all_bounds.Left)
dw = min(d_left, d_right)
dh = min(d_top, d_bottom)
set_size(rectangle(center.X - dw,
center.Y - dh,
2 * dw,
2 * dh))