GridData data= new GridData(GridData.FILL_BOTH);
data.widthHint= convertWidthInCharsToPixels(80);
data.heightHint= convertHeightInCharsToPixels(nLines);
control.setLayoutData(data);
viewer.addTextListener(new ITextListener() {
public void textChanged(TextEvent event) {
if (event .getDocumentEvent() != null)
doSourceChanged(event.getDocumentEvent().getDocument());
}
});