Howto set outputdirectory with google eclipse plugin?

Question

I'm using the Google Eclipse Plugin for GWT development. To do the configuration stuff there's a folder .settings with two files com.google.gdt.eclipse.core.prefs and com.google.gwt.eclipse.core.prefs. These files are a kind of propertie-files.

Now I'm trying to set two different directories for source and output files. But I can't find any documentation about these files.

What I got till now is this.

eclipse.preferences.version=1
jarsExcludedFromWebInfLib=
lastWarOutDir=myoutputdirectory
warSrcDir=war
warSrcDirIsOutput=false

But using this, at compilationtime it opens a filechooser-Dialog on myoutputdirectory every time, waiting for confirmation.

So I ask, is there a solution to setup a different outputdirectory or does anybody know where I can find more Information about the usage of these setting-files.