OK, yes we've found some things that aren't features.
The standard Windows “undo” command is Ctrl+z and it does have an impact. The problem to resolve is that the insertion of a single string gets removed, but the insertion of two (or more) strings isn't completely undone with the hot key.
WriteR asks me if I want to save my work, even if the last action I took was to press Ctrl+s (for save).