Bug 34221 [code manipulation] Comment and uncomment code
The same key ctrl-/ should be used for both comments and uncommenting code. If code isn't commented ctrl-/ will comment. If already commented ctrl-/ will uncomment it. If two levels of comments, uncomment the first, then the second. For example //this is a comment ////this is a second comment hitting ctrl-/ would result in this is a comment //this is a second comment
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
Preferences preferences= JavaCore.getPlugin().getPluginPreferences();
		return preferences.getInt(CODE_FORMATTER_TAB_SIZE);	
	}
	
	private void startTabConversion() {
		if (fTabConverter == null) {
			fTabConverter= new TabConverter();
			configureTabConverter();
			fTabConverter.setNumberOfSpacesPerTab(getTabSize());
			AdaptedSourceViewer asv= (AdaptedSourceViewer) getSourceViewer();
			asv.addTextConverter(fTabConverter);
			
			asv.updateIndentationPrefixes();
		}
	}
	
	private void stopTabConversion() {
		if (fTabConverter != null) {
			AdaptedSourceViewer asv= (AdaptedSourceViewer) getSourceViewer();
			asv.removeTextConverter(fTabConverter);
			
			asv.updateIndentationPrefixes();
			fTabConverter= null;
		}
	}
	
	private boolean isTabConversionEnabled() {
		IPreferenceStore store= getNewPreferenceStore();
		return store.getBoolean(SPACES_FOR_TABS);
	}