In a previous post I wrote about why I preferred GPL license for SimpleDBM. But I am no longer sure; my intention was always to ensure that SimpleDBM can be used by anyone without worrying about licensing issues, and I have no desire to put restrictions on other people's work. So if someone enhanced SimpleDBM, they should be free to do whatever they like with their enhancement, and although it would be nice if they contributed back, I don't insist on it. But this philosophy is very different to the GPL, which asserts that any enhancements should also be GPL.
I also did not fully understand the restrictions that GPL poses on linking with another library. Users of SimpleDBM should definitely not have to change their license or adopt GPL just to be able to use SimpleDBM in their applications.
I am seriously considering changing the SimpleDBM license to some other; probably Apache Version 2.