Bug 16181 Tab key doesn't work in editor when 'Insert spaces for tabs' enabled
Using integration build 0515, pressing Tab in an editor window doesn't do anything when 'Insert spaces for tabs' is selected. The editor is marked as unsaved, but no spaces appear.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
public void setLineTracker(ILineTracker lineTracker) {
			fLineTracker= lineTracker;
		}
		
		private int insertTabString(StringBuffer buffer, int offsetInLine) {
			
			if (fTabRatio == 0)
				return 0;
				
			int remainder= offsetInLine % fTabRatio;
			remainder= fTabRatio - remainder;
			for (int i= 0; i < remainder; i++)
				buffer.append(' ');
			return remainder;
		}
		
		public void customizeDocumentCommand(IDocument document, DocumentCommand command) {
			String text= command.text;
			if (text == null)
				return;
				
			int index= text.indexOf('\t');
			if (index > -1) {
				
				StringBuffer buffer= new StringBuffer();
				
				fLineTracker.set(command.text);
				int lines= fLineTracker.getNumberOfLines();
				
				try {