Bug 33389 Read-Only files: Quick fix enabled and gets checkmark!
RC1 1. set a file to ready only. 2. Open the file an set the cursor inside 3. Open the 'Edit' menu. Note that 'Quick fix' is enabled, but 'Content assist' is not 4. Choose 'Quick fix' 5. Open the context menu: Quick fix got a checkmark!
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
final char fExitCharacter;
		final char fEscapeCharacter;
		final Stack fStack;
		final int fSize;
		
		public ExitPolicy(char exitCharacter, char escapeCharacter, Stack stack) {
			fExitCharacter= exitCharacter;
			fEscapeCharacter= escapeCharacter;
			fStack= stack;
			fSize= fStack.size();
		}
		/*
		 * @see org.eclipse.jdt.internal.ui.text.link.LinkedPositionUI.ExitPolicy#doExit(org.eclipse.jdt.internal.ui.text.link.LinkedPositionManager, org.eclipse.swt.events.VerifyEvent, int, int)
		 */
		public ExitFlags doExit(LinkedPositionManager manager, VerifyEvent event, int offset, int length) {
			
			if (event.character == fExitCharacter) {
				
				if (fSize == fStack.size() && !isMasked(offset)) {
					if (manager.anyPositionIncludes(offset, length))
						return new ExitFlags(LinkedPositionUI.COMMIT| LinkedPositionUI.UPDATE_CARET, false);
					else
						return new ExitFlags(LinkedPositionUI.COMMIT, true);