Tk Source Code

Try the following script:

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set bold [list [font configure TkTextFont -family] [font configure TkTextFont -size] bold]
pack [text .t -font TkTextFont -undo yes]
.t tag configure bold -font $bold
.t insert insert "the last word is "
.t insert insert "bold" bold
.t insert insert "."
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Now do the following:
1. Select the word "bold"
2. Delete this word (press DEL)
3. Undo the change (press Ctrl-z)

After the undo the word "bold" has the wrong font. The undo/redo mechanism should regard the tags, otherwise the result is wrong. E.g in my application I'm using special fonts with the use of tags. If I enter a special symbol "\u0001" of this font (with the appropriate tag), after delete & undo this symbol will be shown with the wrong font, that means it is the wrong text (garbage in this case).

Bad, the current undo/redo mechanism is quite useless.

Although not clear enough in the docs, the undo mechanism only handles insert/delete operations - not tag operations.  Could use to update the docs to note this more clearly.