When k3b is set to verify the written disk (DVD-R in this case), it ejects and reloads it before it attempts the verification. When the disk is loaded, the [0]"A new medium has been detected. What do you want to do?" dialog appears. This is what IIRC Windows do on these occasions when it's clear one has already decided and specified what to do. Patently annoying. [0] http://www.kde.org/announcements/visual_guide_images-3.5/device-popup.png
You can disable the feature via control center --> periphericals --> storage media --> advanced. If you like it, but don't want it when using K3B, you have to look at bugs.kde.org if someone already requested supression of this behaviour and otherwise to open your bug there. Personally I wondered, when this was announced as "great feature", because I hate it having the os/desktop advising me what to do next...
(In reply to comment #1) > look at bugs.kde.org if someone already requested supression of this > behaviour and otherwise to open your bug there. I've cut'n'pasted this as KDE [1]bug #121157. [1] http://bugs.kde.org/show_bug.cgi?id=121157