KDE 4.4.1 SC, K3B 1.91.0, PCLinuxOS 2010 beta2.
After installing PCLinuxOS 2010 beta2 and using it for a few days, I replaced an ATAPI DVDRW with a SATA DVDRW drive.
-Today, after booting for the first time, I inserted a blank CDRW into the SATA drive.
-Device notifier declares a blank CDRW was plugged in.
-I click the left side of the CDRW icon on Device Notifier, I select K3B create a file project.
-K3B opens.
-Status bar shows: "Available:651.9 MiB of 651.9 MiB"
I right click to select a folder that has 821.7 MiB capacity, I select to "add to project".
BUG: the status bar now shows: "Available 3.6 GiB of 4.4 GiB". The Status bar should have turned RED to indicate an error of trying to put 800+ Megs of data onto a 650 megs disc. The error should be displayed at this point. I should not need to wait until I click to burn the data and THEN find out that I added too many files. Or present an error dialog that allows me to change media for the project.
Carrying on past the error, select the file inside the project, remove that folder, status bar reverts to: "Available:651.9 MiB of 651.9 MiB".

Thinking this might be related to the devices registered within K3B, I visited "Settings menu - Configure K3B - Devices icon".
The new SATA DVDRW is listed up top, the old ATAPI drive is listed on the bottom.

How do I remove the older ATAPI entry?

i also find this behaviour a little confusing, i suggest you open a bug report for this on bugs.kde.org, describing how you think it should work. then it will be addressed by the developers at some point

Currently data project is media-agnostic (in contrary to KDE3 version, there were separate "DVD data project" and "CD data project"), that's why the bar resizes itself. You can constraint it by right-clicking it and choosing "From Medium...". You can also manually choose the size of medium.

Ahh. A feature that I was not expecting.
In any event, the way it should work would be modal:
a] turn red if I exceed the capacity of the disc which has already been inserted.
b] if no disc already inserted, the agnosticism can stand as is, I guess, but K3b still needs to respect the actual capacity limits of the currently selected burner hardware.

In other words, there is no sense telling me I could burn my selected 12Gigs to a Blu-Ray disc if only CDRW hardware is attached and configured in K3b - just tell me 'not possible' or 'too big' or some such, BEFORE I click to burn.