With wish8.6.5 a severe bug has been introduced, test the following script:
This is the result since wish8.6.5:
This is obviously wrong, the revised implementation – and versions before wish8.6.5 – are producing the right result:
At this place I like to emphasize that I didn't report any of these bugs to the Tk team. This is the result of my experience, in last eight years the Tk team did ignore most of my error reports, and some of these errors were severe (like endless loops). This behavior is unserious, and unreasonable. I'm sure that this behavior is also the main reason that Tk is quite unpopular. The popularity of software does not only depend on functionality, it also depends on robustness and friendliness. Ignoring error reports is very unfriendly, and the loss of robustness is the consequence of this ignorance.