Eclipse Common Navigator Framework

I have an Eclipse Common Navigator (specific to our project ) on our RAP application. So, generally, when user a resource in the left hand side navigator, it gets opened in the right hand side navigator.Now,suppose, if a click a file with some extension, I want to open a custom message opened and popped up in front of the user in the form of a Dialog Box. how can I achieve this

Alternatively you can register a specific editor with an associated launcher:

<editor
        id="com.foo.MyEditor"
        launcher="com.foo.MyEditorLauncher"
        default="true"
        extensions="your_extension_here"
        icon="any icon for your file"
        name="Dialog editor">
 </editor>

And implement the launcher to show the dialog you want:

public class MyEditorLauncher implements IEditorLauncher {
    @Override
    public void open(IPath path) {
        Shell shell = Display.getDefault().getActiveShell();
        MessageDialog.openInformation(shell, "Not Editable", "Can't open this element");
    }
}

The user will be always be able to use alternative editors, but by default they'll get that message.