I think I've fixed the "+" problem in gcalctool version 4.3.15.
See bug #124172. Mattias, can you confirm that the "+" symbol
is on the bottom half of the key (i.e. shift key is not needed)
please?

And I'm guessing that the "=" key is on the top half of a key
software (i.e. you need to press the shift key to get it to
work). Please confirm. If that is that case, then I still
need to fix that problem.

Thanks.

Yes, = is on the top-half part of the key (i.e. shift is needed) and 
it's on the same key as 0 (zero). The + symbol is on the bottom half 
of the key and the key can be found right next to 0.

Created attachment 21767 [details]
Fix for the problem.

Changes checked into CVS HEAD. Fixed in v4.3.19.
Mattias, if you have the means to check this out
of CVS, build it and test it, I'd appreciate your
feedback. Thanks.

I did a CVS checkout (got 4.3.25) and now '+' works, but '=' still
doesn't work I'm afraid.

And, in my original report I forgot to mention another key that
doesn't seem to work, and that's the '/' key. The '/' symbol is also
on the top half of the key, you press Shift-7 to get it.

Mattias, could you add the following line in gtk.c
in the kframe_key_press_cb() routine, just before
the switch statement (about line 1350):

fprintf(stderr, "kkp_cb: keyval: %d state: %d\n", event->keyval,
event->state);

and rebuild gcalctool.

Then click on the "/" and the "=" keys and let me know what
output the debug message gives.

Thanks.

Sure, here goes:

'=' kkp_cb: keyval: 61 state: 1

'/' kkp_cb: keyval: 47 state: 1

Created attachment 21992 [details]
Fix for shift "=" and shift "/"

Thanks Mattias. Okay, I think I have a correct fix now.
Changes checked into CVS HEAD (also the second attachment
to this bug). Fixed in v4.3.26 of gcalctool.