Update treectrl.tcl

[Meshparts]

Further bug fixes ocuring in special situations (see new added comments)

[apnadkarni]

I will need more time to look at this. It seems to me that the correct selection fix (the shift case) would be to also track the window that had the selection and not just check whether the index exists in the new window because otherwise, if the new window did have a valid item (at the index in the old window), the selection would wrongly include that item from the current window. Am I wrong?

Also, has the indentation been changed? If possible, please try and keep it the same to make it easier to diff.

Thanks for taking the time to submit your contributions!

[Meshparts]

I will need more time to look at this. It seems to me that the correct selection fix (the shift case) would be to also track the window that had the selection and not just check whether the index exists in the new window because otherwise, if the new window did have a valid item (at the index in the old window), the selection would wrongly include that item from the current window. Am I wrong?

Also, has the indentation been changed? If possible, please try and keep it the same to make it easier to diff.

Thanks for taking the time to submit your contributions!

Yes, you might very well be right.
This was a fix from me done quite a few years ago.
I was happy to avoid that error and had no other issues after that.
The indentation is different, because I hat the changed procedure in my main code, which uses different indentation.
Sorry for that.