Eclipse DDT Include Path

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I'm using Eclipse with DDT but it does not find all of the imports

In my dub.json i have
   "importPaths" : ["/usr/include/dmd/gtkd3"],

and this works well with dub but in Eclipse the 'Open Definition' 
feature does not work with 'gtk.Window' for example and gives an 
error: 'Symbol gtk.Window has no source range info!'.
It works with 'std.stdio' etc.

should i add the path to dmd.conf directly or can i set it only 
for the project in eclipse?