Windows 10/11
The new version of the Windows 10/11 PowerToys Toolkit (v0.73) includes the Crop and Lock tool for creating interactive mini-windows. The Crop and Lock utility works in two modes:
Thumbnail ("Thumbnail") - the cropped window updates information from the original window, but does not respond to user actions;
Reparent - the cropped application window responds to user actions (errors may occur in some applications).
To start the Thumbnail mode use the key combination Windows+Ctrl+Shift+T, for Reparent - Windows+Ctrl+Shift+R. The window to be cropped must be in focus.