Use View -> Quick Documentation or the corresponding keyboard shortcut (depends on OS and Keymap).
On Mac OSX with Eclipse keymap, F2 Works.
It's also possible to enable automatic JavaDoc popup on code completion in Preferences -> Editor -> Code completion (Autopopup documentation).
At the beginning this worked for me (somewhat clitching), but now it no longer works :(
To run the Headless-App-Tests in JUnit (e.g. for debugging), create/add a new JUnit Configuration. In the configuration, it is important to select "class" at the dropdown for the "Form mode" (upper right). I also recommend to use "Single instance only".
If "Fork mode: class" is not selected, JUnit seems to use different JVMs to execute test and parameter method, which causes the ArticleManager in the test method to be empty.
By default IntelliJ has different order of import statements as Eclipse. To avoid having these change every time a class is edited in the different IDEs, we should adjust the order in IntelliJ. This can be done under Code Style -> Java - > Imports. The order should be:
import java.*
<blank line>
import javax.*
<blank line>
import all other imports
<blank line>
import cc.denkbar.*
import com.denkbares.*
import de.*
<blank line>
import static all other imports
The above order will not quite avoid all changes, since Eclipse seems to additionally add blank lines between all all imports with different first path elements, but its close enough.
I think since it is a code style, this should also be part of the code style settings, which are also attached to this site.