[GNC] How to change size of register in Gnucash 3.4

[Liz]

Debian Linux
Build ID: 3.4+ (2018-12-30)

I had the registers set so that I could open 4 without overlapping on
my screen.
With Gnucash 3.4 they all got wider and now take up more screen space
than I desire.

With the mouse pointer I can make wider still but I wish to make them
narrower, and it doesn't wish to make it as narrow as I wish.

I've tried altering WindowGeometry in Account.gnucash.gcm but this
doesn't seem to have any effect at all.

Liz