Windows 1.0 Development Release 4

Windows 1.0 Development Release #4 was the fourth release in a series of Development Releases of Windows 1.0, which was compiled on 31 August 1984 and sent to developers in the following weeks. Photos of this build's installation media and release notes were posted by BetaArchive member Allosgroup on 8 July 2021. Similarly to the next release from October, it comes on three 360k disks.

According to the available release notes, this release added support for cooperative multitasking, the ability to paint filled ellipses and rectangles among other GDI improvements, and Atom functionality. It also introduced a new resource format and resource compiler.