Tk Source Code

ttk::treeview never releases or deletes tags, leading to a memory leak

Trigger script

package require Tk
ttk::treeview .t
set id 0
foreach n {100 1000 10000 1000 100} {
    for {set i 0} {$i < $n} {incr i} {
        set item [format {Item#%05d} [incr id]]
        .t insert {} end -text $item -tags $item
    }
    puts "Items: $n\nNumber of tags: [llength [.t tag names]]"
    foreach tag [.t tag names] {
        .t tag remove $tag
    }
}

"Items" and "Number of tags" should be equal but the last number is always increasing

TIP #574 now accepted, and implementation is merged into trunk.
Good job! Thanks Emiliano!

Thank you!

I have written the required TIP, see TIP #574

Also, I have committed your code and patch to branch tip-574.

Attach a patch with a simple test

The solution is to bring the tag facility in line with the one in the [text] widget, which provides [tag remove] and [tag delete] subcommands.
The first one allows removing the tag from a given range of characters (including all characters in the widget, using [$text tag remove $tag 1.0 end]). This, however, doesn't delete the tag information, and it still shows in the [tag names] subcommand. This is exactly the same functionality of the  [tag remove] in the treeview widget.
The [tag delete] subcommand performs a complete deletion of the tag information, including the removal of the tag from the widget and the tag configuration. It will not show in the [tag names] subcommand anymore.

Attached patch implements the [tag delete] subcommand for the ttk::treeview widget.