After experimenting a bit like you did, my perception is that the on and off times on windows is the same (when <code>GetCaretBlinkTime()</code> is not <code>INFINITE</code>). I could go for this change on Windows, i.e. replace the defaults values of <code>-insertofftime</code> and <code>-insertontime</code> by what <code>GetCaretBlinkTime()</code> returns. Then the Tk app still has the possibility of changing the cursor flash rate using the existing widget options. However, letting Tk honor user changes of this system setting <i>while the Tk app is running</i> seems however going a bit too far, and does anyway not sound as a good idea to me.

So this has to be done for the text widget, but also for the entry widget, the spinbox and the canvas. That is, all widgets featuring a possibly blinking cursor. Well, OK that's possible.

Question: is there a similar system call on Linux and OS X providing on and off times of the cursor? How to implement the feature on those two platforms?