Sometimes in Design view, after selecting a text block e.g. <p> element, it is impossible to change the element, to e.g. a heading, by using the element drop down box on Format Toolbar 1. The box is not greyed out. There are no other symptoms.
To recover you must close and reopen KompoZer.
Steps to reproduce:
1. Open KompoZer.
2. Open one file
3. Open a second file
4. Try to change an element in the first file. It cannot be changed
5. Try to change an element in the second file. It can be changed.