"reference existing ecore" browse button of new project wizard doesn't work in some situations

[dvojtise]

in the new K3 project wizard, the "reference existing ecore" browse button doesn't work in some situations. step to reproduce, open an editor, do some selection in it, then File > new > project > K3 project, the "reference existing ecore" browse button fails with the following exception

java.lang.ClassCastException: org.eclipse.jface.text.TextSelection cannot be cast to org.eclipse.jface.viewers.IStructuredSelection at org.k3.language.ui.wizards.pages.WizardPageNewProjectK3Plugin.workspaceDialog(WizardPageNewProjectK3Plugin.java:322) at org.k3.language.ui.wizards.pages.WizardPageNewProjectK3Plugin$8.widgetSelected(WizardPageNewProjectK3Plugin.java:241)

however, if the selected element before the starting the new project wizard is a resource in the explorer then it seems to work.