public void showAssignmentDialog(DocumentFrame documentFrame) {
if (currentFrame==null||!getCurrentFrame().isActive())
return;
if (assignResourcesDialog == null) {
assignResourcesDialog = new AssignmentDialog(documentFrame);
assignResourcesDialog.pack();
assignResourcesDialog.setModal(false);
}
assignResourcesDialog.setLocationRelativeTo(documentFrame);//to center on screen
assignResourcesDialog.setVisible(true);