Use of the global variable ::tk_patchLevel is out of date. In modern Tcl/Tk programs, use [package present Tk] to find out what release of Tk is in the current interp.

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From the tkvars man page:

• Contains a decimal integer giving the current patch level for Tk. The patch level is incremented for each new release or patch, and it uniquely identifies an official version of Tk.

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