Editing a EclipseRCP Project with IntelliJ (instead of Eclipse)

Question

I am currently working at a company which is using EclipseRCP for its projects. Since I am very used to IntelliJ (from my experience at the university), I would like and tried to use IntelliJ.

The problem is that all of the classes are not accessible with the point operator.

import org.eclipse.e4.core.dir.annotations.Optional;
import org.eclipse.e4.core.dir.annotations.Preference;
...
import org.eclipse.swt.widgets.label;

public class DirControl {
   Label dirLabel;

   @PostConstruct
   public void postConstruct(Composite parent){
     dirLabel = new Label(parent, SWT.NONE);
     dirLabel.setText("test");
   }
}

In this example I'm not able to get the suggestions that the label has methods (setText, setToolTipText ...).

Maybe the problem is related to the plugin dependencies which are unique to Eclispe (and EclipseRCP)? But I am not quite sure about that.

I've tried out the OSGI Plugin from the IntelliJ Appstore and the option "Open Module Settings" with changing the dependency storage format to Eclipse.

My colleagues and I would be extremely happy if anyone knows what the problem is and how to solve it.