1. Have multiple Maven (or JDK) installations configured. Then when some particular Maven (or JDK) is chosen in job configuration and then later the Jenkins configuration is modified to include only one Maven (or JDK) entry, the affected job configuration still sticks to some (previously chosen) particular option even though it doesn't exist anymore and it isn't possible to fix it via GUI (without adding some dummy Maven of JDK entry) - perhaps due to JENKINS-659 . I believe that in such cases when only one Maven, JDK, etc... entry exists and some particular one is used in the job configuration there should be an option to pick the desired one still visible in the GUI - or even better to remove the particular selection and stick to default (the only one which does exist).

2. Similarly, there's no way to remove the particular Maven selection from the job configuration in the GUI. One can only select one or another, but not remove the selection and leave it to "defaults". The config.xml has to be edited in order to achieve this.

3. With JDK selection there's an inconsistency in the behavior compared to Maven selection. As mentioned in 2nd point, for Maven one or another is picked with seemingly the first one in the list of configured ones being picked by default. For JDK, there's an additional "default" entry which causes a little troubles - it doesn't mean that any configured is JDK picked by default (the first in the order etc), but instead an OS default is used which is quite strange. It's strange because when you narrow down the configured JDKs to just one, that one is used by default, but when you add more, not single one is used by default and the OS default (just "java" inetead of "/full/path/to/java") is used instead.

Other components such as ant etc may be affected as well.