Editor buttons disabled when invalid macro used

When editing a document in Confluence if you enter a string containing curly-braces and '$' the editor thinks it's a macro. It isn't a valid macro, nothing is reported but the Preview/Save/Cancel buttons at the bottom are disabled. This leads to users continue to edit their document until they're done and then find out it can't be saved. Work is lost. Frustration ensues.

To reproduce:
1. edit a document
2. enter '{$foo}'