This is a a wonderful tool. I am surprised why Microsoft did not invest in creating such a tool and left developers astray.

There is a bug in publishing. This is how CRM works. If you want to check an attribute's value with null in the ribbon, you have to used Value="". You cannot use Value="null".

However, if you have a display rule and want to check for empty value, publishing fails. This is because the editor does not add Value attribute if left blank. This leads to error while publishing.