Detect and view locked and unlocked cells in Excel

While creating complex Excel based data input forms many cells needs to be protected from user input, like input labels, table titles, etc... When giving form to production I must be sure that all cells are properly locked. But, how to be sure if this having 1000+ cells ?

I discovered simple and visual technique to quickly detect and show locked and unlocked cells using Excel 2003 or 2007/2010.