Re: blink-cursor-mode and active fields

[Richard Stallman]

    When blink-cursor-mode is disabled, the cursor becomes invisible under
    the following circumstances: (i) when the cursor is located on certain
    kinds of "active" (i.e. clickable) fields (e.g., those in
    customization buffers, in Gnus group buffers, in the recentf "more"
    buffer -- but not on active fields in a *Help* buffer) and then the
    mouse pointer is moved over the field; (ii) when the cursor is placed
    on one of these active fields by a key combination (e.g. `C-x o' where
    point in the other window is on the active field) and the mouse
    pointer is located on the field; (iii) when the cursor is placed on an
    active field by a mouse click on the field.

Does this depend on your customizations?  It does not fail for me
using the latest sources in CVS.  Perhaps it is fixed since 21.2.