Tcl/Tk 9.1

Latest Release: Tcl/Tk 9.1.0 (Sep 29, 2026)

Tcl/Tk 9.1.0 is the current development work on Tcl and Tk, aiming toward stable releases in September 2026. They add new features and interfaces to the foundation of Tcl/Tk 9.0.

Download Tcl/Tk 9.1.0 Source Releases

Highlights of Tcl 9.1

• New command unicode: Unicode normalization
• New C routines Tcl_UtfToNormalized*: Unicode normalization
• New command timer: monotonic clock; microsecond resolution
• New command lfilter: select items from list
• New command interp set: variable access in child interpreter
• New subst options: -backslashes, -commands, -variables.
• New switch options: -integer.
• Many C99 math routines now available as expr functions.
• Applications now required to call an initialization routine, either Tcl_FindExecutable or TclZipfs_AppHook.
• New C routine Tcl_IsEmpty.
• New C routine Tcl_GetEncodingNameForUser.
• New C routine Tcl_AttemptCreateHashEntry.
• New C routines Tcl_ListObjRange, Tcl_ListObjRepeat, Tcl_ListObjReverse.
• New C time API using long long in place of Tcl_Time
• Case-insensitive filesystem paths on macOS.
• auto_execok and exec search reform on Windows.
• Revised searches for script library and encodings.
• Improved list internals for memory efficiency of large lists.
• Extended support for 64-bit sizes.

Highlights of Tk 9.1

• Accessibility screen reader support.
• Initial support for bidirectional text / RTL languages.
• New widget ttk::toggleswitch.
• New command tk attribtable.
• send command revised and improved on Aqua.
• Handling of negative screen distances.
• Extended states in ttk::treeview and ttk::notebook
• Improvements to Tk_CanvasTextInfo
• Rotated text on labels
• Limit message box and dialogs to physical screen width.
• Improved listbox selection colors.
• Removed obsolete support for Windows XP appearances.

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