: If you prefer a local setup for better performance, enthusiasts often recommend using VirtualBox
Drag the Clock window over the Paint window. In 1987, this was revolutionary. In the simulator, notice the "System Menu" icon in the top-left corner of each window (the little dash - ). Click it to see "Move," "Size," and "Close."
is an excellent blog post. It covers its evolution from a "simple shell" into a complex 32-bit hypervisor in the Windows/386 edition.