We are using doxygen for a C++ project. The quick link index at the beginning of the alphabetical list of classes in classes.html is supposed to provide a convenient way to jump to classes starting with a particular letter. This feature doesn't work in release 1.8.11; clicking on a letter in the quick link index has no effect. Experimentation shows that this feature worked in release 1.8.5 but fails in release 1.8.6 and all subsequent releases, including 1.8.11.

Examination of the html source for the list shows that the quick links always refer to "#letter_<upper_case>" while the cells they are supposed to refer to are named "#letter_<lower_case>", for instance "#letter_E" and "#letter_e", respectively. Further experimentation shows that cell name is lower case if the first letter of the class name (after the prefix has been removed) is lower case and upper case if the first letter of the class name is upper case. So the quick links work if the class names begin with an upper case letter. See for instance the vtk document at http://www.vtk.org/doc/release/7.0/html/classes.html, generated by doxygen 1.8.9.1.

Examination of the release 1.8.11 C++ source in index.cpp shows that the references in the quick links are generated using:

line 1779:      startLetter=getUtf8CodeToUpper(cd->className(),index);

while they cells they refer to are generated using:

line 1830:      startLetter=getUtf8Code(cd->className(),index);

These will match only if the letter at index in className is already upper case. 

Changing line 1830 to match line 1779 fixes the problem.