I think it's Widgets on Windows that is out of line here, as I indicated
before. All the non-Widgets programs I have tried on Windows that
allow customisation of shortcuts show CTRL + = in the input box if
you hold CTRL and press the +/= key. If you set that shortcut, the
menu shows CTRL + = .
After all, other keys do not show the SHIFT variant of the key even
if you hold the SHIFT key with them e.g. holding SHIFT and pressing
the ( / 9 key enters SHIFT + 9 in the input box in Audacity, not
SHIFT + ( .
On Windows yes like Bill sees, browsers hack CTRL + + to perform
zoom in, but neither IE, Firefox or Chrome actually let you change
keyboard shortcuts without adding extensions.