The very first time that you bring gcalctool up, you
do not get memory registers. But gcalctool will remember
certain state information, one of which is whether you last
had memory registers showing. The next time you start gcalctool,
(if you had the register window open), it will be displayed.
This (and the other state settings) are described in the 
online help.

Cc:'ing Calum for his input on this.

I definitely agree it should remember your previous state - perhaps 
I had state left over from trying it a long time ago.
If it's not there by default that's all I was suggesting,
can close the bug.

Just to double check I did:

% rm -rf ~/.gconf/apps/gcalctool
% gcalctool

and gcalctool came up with no initial memory register window.

Closing as not a bug. 

Thanks.

Reopening. Dennis Cranston discovered that the gcalctool
schemas file had the default value for the "showregisters"
resource set to true. Gotta fix that.

Change made. Fixed in v4.2.73. Thanks Dennis.