There was a bug in the recent marker work where markers weren't getting removed from lines if you picked "none". I had disabled the code that makes the 'none' marker work, because doing so prevented an event cascade.
So this fixes the event cascade - basically, this temporarily disables the "changed" signal handler when we're updating the marker menus, so the changes don't trigger additional "changed" signals.
There is still one bug I know of - if you click on one of the numerical entry boxes on the stroke style page, before clicking the marker dropdown, then when you open the marker dropdown you see two separators rather than 'None' and one separator. But this bug has been around for quite some time.
Let me know if you spot any other bugs.
Bryce