With Editor toolbar (that currently only include a combobox that show class 
members) turn on, I observe some cases that the combo box blank:

- If there's only one opened file, the combobox on editor toolbar always blank. 
When you open addtional files, editor toolbar for newly opened tabs will be OK. 
When you close all editor tabs to let only one left, the combobox will become 
blank again, even though it may be OK before (because it didn't belong to the 
first file opened)

- If you exit Netbeans with some file still opened in editor window, when you 
rerun Netbeans all toolbar for available (opened) editor windows (tabs) will 
have this combobox blank.

As I find the edior toolbar valuable for navigating in long editing file, this 
bug should be fix soon.