MacOS 26's window corner radius inconsistencies have frustrated users who find the system's varying roundness across apps visually jarring. The issue stems from Apple's inconsistent design choices, with apps like Safari displaying particularly aggressive corner rounding that clashes with other system elements. Many users consider the aesthetic choices excessive and poorly implemented.

Some users have resorted to disabling System Integrity Protection to modify corner radii, but this security trade-off concerns many. The author argues that rather than making everything less rounded, a better solution would be making everything consistently rounded. This led to creating a dynamic library tweak that forces uniform corner radii across all third-party apps.

The solution involves swizzling NSThemeFrame methods to override corner radius calculations, compiled as a dynamic library loaded via DYLD_INSERT_LIBRARIES. The approach targets third-party GUI apps while skipping Apple's own applications and system tools. While the fix addresses visual inconsistency, it represents a workaround for what many see as questionable design decisions in MacOS 26's interface.