Thanks, Grandfather,

However, part of the point of using optional scrollbars is that, of course, I only want the scrollbars to appear when they're necessary.

So thanks for confirming that using non-optional scrollbars (changing "osoe" to "se" in my example) would make to the bug go away.

But I am still interested in the larger problem of:

• Is this a known (eg. reported) bug?  Why do optional scrollbars cause this bug to occur?
• Is there some known workaround for this that I should be using?
• Does that happen with other Scrolled widgets than "ROText" and "Text"?
• Is there a better workaround than that of seeking elsewhere in the ROText widget, updating, and then seeking to the end?